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WITED STATED PATENT OFFICE 



THE CLASSIFICATION OF PATENTS 




WASHINGTON 

GOVERNMENT PRINTING OPFICE 

1917 









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UNITED STATES PATENT OFFICE 



THE CLASSIFICATION OF PATENTS 




WASHINGTON 

GOVERNMENT PfiMTING OEEICE 

1917 



D. of D. 

SEP 24 191 r 



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PREFATORY NOTE. 



Parts A and B of the following pages are designed to acquaint all 
persons using the Patent Office classification with the principles upon 
which the reclassification is proceeding. 

Part C consists of a few tentative rules advanced with the notion 
of fij^ing classification practice within the office in certain doubtful 
cases. 

Part D is intended to mform examiners reclassifying within exam- 
inmg divisions respecting the initial procedure in reforming a class. 

3 



CONTENTS. 



Page. 

A. Introduction 7 

Past classifications of the U. S, Patent Ofiice 7 

Beginning of revision S 

Precedents and authorities 9 

Definition of scientific classification 10 

B. Principles of the new classification of the Patent Office 10 

Elements of a Patent Office classification 10 

Basis of classification 11 

Art as a basis 11 

Function or effect as a basis 13 

Structure as a basis 14 

Division and arrangement 15 

Infinitude of possible combinations 16 

Division and arrangement in the natural sciences 16 

Difficulty of entitling a subclass corresponding to every combi- 
nation 17 

Expedients to reduce the number of subdivisions 18 

Superiority and inferiority 21 

Definite positional relationship of subdivisions 21 

Indented schedules 23 

Bifurcate division 24 

Utility of arrangement according to resemblances 25 

Definition 26 

Cross-references and search-notes 27 

Diagnosis to determine classification 28 

Claimed or unclaimed disclosure. 28 

Diagnosis of pending applications 29 

Difficulties due to varying ideas of claims 30 

C. Rules of classification 31 

Basis of classification 31 

. 1. "Art" as the basis 31 

2. Operative or manipulative arts 31 

3. Structures 32 

4. Composition of matter and formed stock 32 

Division and arrangement 32 

5. Exhaustive division; miscellaneous subclass 32 

6. Subclasses not to overlap 32 

7. Subclasses of any group to be formed on one basis 33 

8. Apparent exception to rules 6 and 7 33 

9. Relative position of subclasses 33 

10. Indention of subclasses 34 

11. Different kinds of titles for subclasses 35 

12. Arrangement to limit search and cross-references 35 

Definition 36 

13. Tentative definition 36 

14. How to define 36 

15. Explanatory notes may sometimes displace definition 37 

5 



6 INDEX. 

C. Rules of- classification — Continued. , . Page. 

Cross-references and search-notes i 37 

16. Impossibility of cross-referencing all disclosures 37 

17. Occasion and direction of cross-referencing 37 

18. Occasion and scope of search-notes 37 

Diagnosis to determine classification. . , 38 

19. Patents diagnosed by claimed disclosure 38 

20. Patents diagnosed by most intensive claim 38 

21. Exception to rule 19, claim for a part of a disclosed combination. 39 

22. Exception to rule 19, claims for a part of a disclosed combination. 39 

23. Exception to rule 19, generic combination old as matter of com- 

mon knowledge 39 

24. Exception to rule 19, article of manufacture defined only by 

material 39 

25. Exception to rule 19, utilizing a composition 40 

26. Exception to rule 19, utilizing a machine 40 

27. Patents having claims for several different inventions 40 

28. General rule of superiority between statutory kinds of invention . 41 

29. Exception to rule 28 41 

30. Process and apparatus 41 

31. Article of manufacture and instrument for making a part of it 

or performing any minor act relative thereto 41 

32. Process and product where search for the process would have to 

be made among machines 42 

33. Process and product where search for the process would have to 

be made among products 42 

34. Process of making a composition and the composition where 

the process is peculiarly adapted to make the composition. . . 42 

35. Article of manufacture or composition and process for making 

one of the parts of the article or ingredients of the composition . 42 

D. Procedure in reclassifying within examining divisions 43 

1. General attitude 43 

Procedure involving only cursory scrutiny of familiar patents — 

2. Consider wholes in forming tentative subdivisions of subclasses. . 43 

3. Write tentative definitions of subdivisions 43 

4. Consider the significance of analogies found to traverse parts of 

two or more existing subclasses 43 

5. Arrange groups on parallel or accordant lines where practicable. . 44 

6. Watch for subcombinations deserving separate recognition 44 

7. Consider whether the groups collectively will constitute a proper 

class and theic best correlation 44 

Procedure involving rigorous analysis — 

8. Diagnose each patent for' original classification 44 

9. Group and consider the disposition of patents deemed foreign to 

the class 44 

10-15. Consider and indicate cross-referencing within and to and 

from the class 45-46 

Note 46 



THE CLASSIFICATION OF PATENTS. 

(A) INTRODUCTION. 



Classification lies at the foundation of the mental processes. Without the power 
of percei^dng, recognizing resemblances, distinguishing differences in things, phe- 
nomena and notions, grouping them mentally according to those resemblances and 
differences, judgment is impossible, nor could reason be exercised in proceeding 
from the known to the unknown. 

* * * * ^ * * 

The facilitation and abbreviation of mental labor is at the bottom of all mental 
progress. The reasoning faculties of Newton were not different in qualitative -char- 
acter from those of a ploughman; the difference lay in the extent to which they were 
exerted and the number of facts which could be treated. Every thinking being 
generalizes more or less, but it is the depth and extent of his generalizations which 
distinguish the philosopher. Now it is the exertion of the classifying and generalizing 
powers which thus enables the intellect of man to cope in some degree with the 
infinite number and variety of natural phenomena and objects. (Jevons, Principles 
of Science.) 

PAST CLASSIFICATIONS OF UNITED STATES PATENT OFFICE. 

As under the patent laws the people of the United States assume 
all the risks in granting a patent for any means of the "useful arts/' 
a classification that will facilitate a judgment respecting the patent- 
ability of any means presented to the Patent Office is of peculiar 
moment. The enormous extent, diversity, and refinement of the 
useful arts preclude the formation of a judgment on novelty within a 
reasonable time, unless the necessary comparisons with known proc- 
esses and instruments have been previously made along the lines 
that searches must follow and the results of such comparisons made 
available in a classification. The vast majority of available dis- 
closures of the arts occur in patents. Hence the Patent Office 
classification must be adjusted in the main to the analysis, diagnosis, 
and orderly arrangement of the disclosures of patents. 

For more than 80 years United States patents have been classified. 
The first pubhshed classification, promulgated in 1830, comprised 
6,170 patents, divided into 16 classes. The change from a registration 
to an examination system in 1836 instigated a new classification in 22 
classes, including 9,800 patents. The next came in 1868 with 36 
classes, including about 75,000 patents. On March 1, 1872, a revised 
classification was adopted, comprising 145 classes, including 131,000 



8 CLASSIFICATION OF PATENTS. 

patents. This classification is said to have been planned by Dr. 
Edward H. Knight. The placing of the patents in accordance with 
the schedule of classes is said to have been done by •the several 
examiners. The class arrangement was purely alphabetical by class 
titles, and the number designations followed the alphabetical order. 
The names of things to be found in the several classes were arranged 
alphabetically under each class title. No attempt was made to 
bring the titles of allied materials into juxtaposition or to effect other 
definite arrangement with reference to subject matter in the printed 
schedules. A consolidated name index supplemented the list of 
names by classes. 

This classification of 1872 is in part the classification that now 
exists, many of the same class numbers and titles being still in use. 
Examiners were apparently permitted to make changes in classifica- 
tion to suit their convenience without notice until 1877. In that 
year a revision of the published schedule was made by a committee 
resulting in the addition of 13 new classes, and examiners were 
ordered to transfer patents in accordance with the new titles. The 
first classification published with distinct subclasses appeared in 1880 
From that time until 1898 the classification grew by addition and 
subdivision of classes to suit the ends of individual examiners or in 
response to supposed exigencies of the work where one division was 
thought to be overloaded and another underloaded, and the alpha- 
betical arrangement of subclasses under each class has succeeded the 
alphabetical list of names. The arbitrary correspondence originally 
established between the alphabetical order of class titles and the 
numerical order was destroyed as soon as expansion of the classi- 
fication began. 

However suitable to the then-existing material of the useful arts 
the classification of 1872 may have been, it failed as fail all inductive 
processes wherein the generalizations are not broad and deep. (Isaac 
Newton's intellect could detect the resemblance between the falling 
fruit and the motions of the planets.) The classification of 1^72 was 
not exhaustive; it failed to recognize to the fullest extent what 
Bishop Wilkins saw nearly 300 years ago, to wit, that there are ''arts 
of arts;" and it failed to provide for future invention of new species 
in the same art, and to recognize that new arts could be formed from 
combinations of the old. 

BEGINNING OF REVISION. 

The Classification Division was created in the hope that guiding 
principles of classification could be developed and applied for the 
purpose of amending or revising the classification whereby patents 
could be placed with greater assurance, and whereby the searcher 



CLASSIFICATION OF PATENTS. 9 

with these guiding princples in mind might find the nearest refer- 
ences. It was confronted with the problem of revising while at the 
same time keeping accurate record of all changes, correcting all 
indexes of patents, and using copies in constant demand for search 
at the same time, necessitating much clerical work, and constant 
interruption — of correcting rather than planning anew; of mending 
a machine while constantly increasing duty was required of it. 

Ideas on the subject of revision were called for by the Commis- 
sioner of Patents, and all in the Patent Office had an opportunity 
to set forth their notions. The views of one met with approval and in 
accordance with those views a ''Plan of Classification" was prepared 
and promulgated in 1900. What other plans may have been sub- 
mitted is not now generaUy known. But in substantial accordance 
with that published plan, the process of revision has proceeded for 
more than 14 years until approximately 50 per cent of the patents 
(including incomplete work) have been placed in revised classes. 

PRECEDENTS AND AUTHORITIES. 

No effective precedents have been found in any prior classifications 
of the arts. The classifications of the principal foreign patent of- 
fices have not been materially different in principle from the United 
States Patent Office classifications of the past. 

The divisions found suitable for book classifications for library use, 
have not been deemed adequate to the exactness and refinement 
essential to a patent office classification of the useful arts. The sys- 
tems of class and subclass sign or number designations of the modern 
library classifications, with their mnemonic significance, afford the 
most important suggestions to be drawn from library classification. 
None of these systems of designation has been adopted, (1) because 
of a serious doubt as to the availability of such designations by 
reason of the length or unwieldiness to which they would attain in 
the refinements of division necessary in a patent office classification, 
and (2) because of the enormous amount of labor necessary to make 
the change from present practice. 

The best analogies are in the known (but changing) classifications 
of the natural sciences, and in them the problems are so different 
that the}^ can serve only to illustrate general principles. The broad 
principles of classification are well understood. The authorities are 
the logicians from the ancient Aristotle to the modern Bentham, 
Mill, and Jevons. The effort of the Classification Division has been 
to adapt and apply these weU-known principles to the enormously 
diversified useful arts, particularly as disclosed in patents and appli- 
cations for patents. 
102807—17 2 



10 CLASSIFICATION OF PATENTS. " 

DEFINITION OF SCIENTIFIC CLASSIFICATION. 

It may be well to insert here an authoritative definition: ^^A scien- 
tific classification is a series of divisions so arranged as best to facili- 
tate the complete and separate study of the several groups which are 
the result of the divisions as well as of the entire subject under inves- 
tigation." (Fowler, Inductive Logic.) 

Investigation and study of any subject will be facilitated if the 
facts or materials pertinent to that subject be so marshaled and 
arranged that those most pertinent to it may appear to the mind in 
some form of juxtaposition. It is the purpose of the Patent Office 
classification to divide and arrange the body and multitudinous units 
of the useful arts so that, having the question of novelty of any defined 
means to answer, one may with reasonable assurance approach that 
portion of the rank of arts in which it will be found if it is not new, 
and in propinquity to which will also be found those means that bear 
the closest resemblances to that sought for, the resemblances of other 
units growing less in proportion to their distance therefrom. 

Success in the fundamental aim of facilitating adequate search 
should evidently at the same time reduce proportionately the danger 
that interfering applications will be overlooked and also effect a dis- 
tribution of labor favorable to the acquisition of special skill. 

(B) PRINCIPLES OF THE NEW CLASSIFICATION OF THE PATENT 

OFFICE. 

THE ELEMENTS OF A PATENT OFFICE CLASSIFICATION. 

A classification will be useful in proportion (1 ) to the pertinence to 
the subject under investigation of the facts selected to be grouped 
together, or, in other words, in proportion to the appropriateness of 
the ''basis of classification" to the subject in hand; (2) to the con- 
venience, stability, and uniformity of the arrangement of the sub- 
divisions whereby the investigator may proceed w^ith reasonable 
assurance to that portion of the rank of groups within which he will 
find cognate material; (3) to the accuracy and perspicuity of the 
definitions of the several divisions and subdivi-ions; (4) to the com- 
pleteness and reliability of the cross-referencing and cross-notations; 
(5) to the uniformity, feasibility, and certainty of the rules by which 
the accessions of patents disclosing one or several inventions may be 
diagnosed and distributed to the appropriate divisions of the classifi- 
cation in accordance with the basis adopted. 

Corresponding to the foregoing analysis the theory of Patent Office 
classification may be treated in five parts: (1) The principles on 
which the arts shaU be divided (basis of classification); (2) subdivi- 
sion and mechanical arrangement of groups; (3) definition; (4) cross- 
referencing and search-notes; (5) the choice of features by which a 
patent shaU be assigned in the classification (diagnosis). 



classificatiojST op patents. 11 

basis of classification. 

The first and most vital factor in any system of classification is the 
basis of division, that is, the kind of characteristics common to any 
number of objects selected to characterize groups, whereby the indi- 
viduals of any group will resemble each other for the purpose in 
view more closely than any individual in any group will resemble 
any individual in any other group. 

^^ There is no property of objects which may not be taken, if we 
please, as the foundation for a classification or mental grouping of 
those objects, and in our first attempts we are likely to select for that 
purpose properties which are simple, easily conceived, and percepti- 
ble in a first view without any previous process of thought — but these 
classifications are seldom much adapted to the ends of that classifica- 
tion which is the subject of our present remarks." (J. S. MiU, 
System of Logic.) 

It is clear that a number of objects may be classified on several 
different bases. For example, a number of books could be divided 
into groups (1) according to the subject of their contents; (2) accord- 
ing to the language in which the books are written; (3) according to 
the size of page; (4) according to the binding material; or (5) accord- 
ing to the color of the binding. Each of these may be useful classi- 
fications for some purpose. For the student of literature none is of 
value except the first; for the connoisseur in bindings, only the last 
three. A classification of animals including classes of land aimals 
and water animals would hardly suit a student of zoology, as it would 
associate with the shad and perch such differently organized creatures 
as the porpoise, whale, and seal. Yet such a classification might 
prove very suitable for a student of fisheries. 

Art as a basis} — So in seeking a basis for a patent office classifica- 
tion the purpose of the classification should be the guide. Allega- 
tions of ulterior uses ^ (such as may be made merely because the in- 
ventor thought of applying his invention to those uses only, or in an 
effort to get the application examined in a certain division) and other 
superficial bases should be avoided. That basis will best suit the 
purpose which effects such an arrangement as will exhibit in suitable 
groups the ''state of the prior art," by which is here meant not neces-. 
sarily all the instruments of a trade or industry, or all the articfes 
sold by a shopkeeper, as a stationer, but those means that achieve 

1 An "art," in the sense of a single unitary invention, is a synonym of process, method, and operation. 
The term "art" is ambiguous in popular usage. In the phrase "useful arts" in the Constitution, it denotes 
the area of endeavor to which the patent laws apply. When the word "art " is used to specify some frag- 
ment of the useful arts, it commonly raises different notions in different minds. It may be correctly used 
to designate any division of the useful arts. It is as proper to speak of the art of grinding or the art of 
moldinig as of the art of metal-working or the art of brickmaking. 

2 A "use" is an application of a means to substance to produce an effect which may or may not be th« 
necessary effect of the means in its normal operation. A cataljiiic may be used to ignite gas or to con- 
vert oleins into stearines. An ice pick may be used to hold a chalk line or prick holes in leather, etc. 



12 CLASSIFICATION OF PATENTS. 

similar results by the application of similar natural laws ^ to similar 
substances. 

As all inventions are made with the ultimate object of satisfying 
some human desire, the utility of an invention appears to be a natural 
basis of classification. It is apparent, however, that most inventions 
may contribute to numerous utilities besides the ultimate one. Many 
processes and instruments intervene between the seed planter and 
the wheaten rolls upon the breakfast table. The plow may be viewed" 
as an agricultural instrument or as an instrument of civil engineering, 
according as it is used for preparing the field for planting or round- 
ing a road. A radiating coil of pipe may be thought of as a condenser 
of steam or of alcoholic vapors, according as it is applied to one mate- 
rial or another; as a cooler or a heater, according to the temperature of 
a fluid circulated through it. A hammer may drive nails, forge iron, 
crack stone or nuts. Underlying all of these ulterior utilities, there 
is a fundamental one to which the normal mind will reach in its 
natural processes and there rest. The plow loosens or turns over the 
surface of earth; the coil effects an exchange of heat between its in- 
terior and exterior; the hammer strikes a blow. A classification of 
plows in agriculture, road building, or excavating, according to stated 
ultimate use; of a radiator coil as a steam condenser, still, jacket- 
water cooler, refrigerator, or house heater; of the hammer as a forg- 
ing tool, a nail driver, or a nut cracker, appears to separate things 
that are essentially alike. But classifying a plow on its necessary 
function of plowing, a radiator on its necessary function of exchang- 
ing heat, a hammer on its necessary function of striking a blow, evi- 
dently results in getting very similar things together. Assuming for 
the moment that utility is a reasonable basis of division of the useful 
arts, it is deemed more logical to adopt as a basis some utility that 
must be effected by the means under consideration when put to its 
normal use rather than some utility that may be effected under some 
conditions. Two of the five predicables of ancient logic are property ^ 
and accident.^ The capacity of the hammer to strike a blow, the 
capacity of the radiator coil to exchange heat, are in the nature of 
properties. The capacity of the hammer to crack nuts, of the coil to 
condense steam, are in the nature of accidents — something that follows 

iBy "natural law" in the useful arts is meant that uniformity of action which is manifested whenever 
any particular substance in any particular condition is brought into such relation with any particular 
manifestation of energy that the force exerted modifies or prevents modification of the form, nature, con- 
dition, or locus of the substance or modifies the manifestation of energy or both. 

2A "property" may be described as any quality common and essential to the whole of a class biit not 
necessary to mark out that class from other classes. Thus, all wheel tires may be said to possess annu- 
laritv; but wasliers and finger rings are also annular. A "peculiar property" is one that not only always 
belongs to a class of objects but belongs to that class alone; thus a circle has the peculiar property of con- 
taining the greatest space within a line of given length, and catalytic substances have the power of setting 
up chemical reac tion without themselves being changed. 

* .\n "accident" is any qualit' that may indilTerently be'ong or not belong to a class without affecting 
the other qualities of the class. That a man's name is James is an accident telling nothing of t'le man's 
physique nr character. 



CLASSIFICATION OF PATENTS. 13 

from the impact and the heat exchange because of the particular 
accidental conditions of operation. To select an accident as a basis 
of classification is contrary to the laws of thought. 

It may be said then that the Patent Office classification is based 
upon ^^art" in the strict sense in which the word may be said to be 
used in section 4886, Revised Statutes, but not necessarily in the 
looser sense of industries and trades. A proper maintenance of the 
distinction between the word ''arts" of the statute and the phrase 
'' industrial arts'' used in the sense of industries and trades is essential 
to an effectire classification for the purposes of a patentrofiice search. 
Similar instruments have been patented in three different classes, be- 
cause of the statements that one was designed for coohng water, an- 
other for heating water, another for sterilizing milk; in four different 
classes, because of the statements that one apparatus was to separate 
sohds from the gases discharged from a metallurgical furnace, an- 
other to separate carbon from the combustion gases of a steam-boiler 
furnace, another to remove dust and tar from combustible gas, and 
another to saturate water with carbon dioxid. Owing to the con- 
tinuance of a classification based largely on remote use, many appli- 
cations come into the office setting forth inventions of very general 
apphcation which nevertheless have to be classified more or less arbi- 
trarily in one of several arts in which they may be used but to which 
they are not limited. 

Function or effect as a hasis.^ — Means of the useful arts are related in 
different degrees. Resemblances selected as bonds for a number of 
inventions may be more or less close. It is axiomatic that close re- 
semblances should be preferred over looser ones for classification pur- 
poses. Processes and instruments for performing general operations, 
such as moving, cutting, molding, heating, treating liquids with gases, 
assembling, etc., are more closely bonded than those for effecting the 
diverse separate successive operations directed toward complex 
special results, such as making shoes, buttons, nads, etc. Means of 
the former sort perform an essentially unitary act — the application 
of a single force, the taking advantage of a single property of matter. 
Those of the latter sort require the application of several different 
acts employing frequently a plurality of forces or taking advantage 
of several properties of matter. In the former case, classification can 
be based on what has been called function, in the latter it can not be 

1 "Effect" or "result" is the consequence of a process of the useful arts practiced with or -without 
instruments. The effect of an instrument is the effect of its operation. Effects may be direct or indirect, 
proximate or remote, necessary or accidental. 

"Product" is an effect consequent upon a process that changes the form, state, or ingredients of matter 
perceptibly and permanently, as distinguished from effects that are fleeting or involve no change in per- 
ceptible form, state, or ingredients of matter. 

"Fimction" is the '-'action of means upon an object while producing the effect." (Eobinson.) Func- 
tions may be direct or indirect, proximate or remote, necessary or accidental. The direct, proximate, 
or necessary function of the hammer in normal operation is impacting. Indirect, remote, or accidental 
functions of a hammer may be comminuting, forging, driving, etc. 



14 CLASSIFICATION OF PATENTS. 

based on function but can be based on what has been called effect 
(or product). 

Function is closely related to cause. It is an axiom of logic that 
cause is preferable to effect as a basis of those classifications designed 
for scientific research. Hence the functional basis is preferred in all 
cases in which it can be applied. A condenser for the fumes of zinc 
is much more like a condenser for the fumes of acid or the vapor of 
water than it is like the art of recovering zinc from its ores, and it 
employs only one principle, to wit, heat interchange. A water-jacket 
for cooling the walls of a gas-producer or glass-furnace is much more 
like a water-jacket for cooling the walls of a limekiln or steam-boiler 
furnace than it is like the art of gas-making or manufacture of glass 
articles. In accordance with what are thought to be the correct 
principles, therefore, the zinc-condenser ought not to be classified as 
a part of the art of metallurgy, nor the ,water-j acket as a part of the 
art of gas-making, merely because these instruments have a use in 
these arts, but should be included, respectively, in classes based upon 
the more fundamental utilities effected by them. 

Although it is evident that molding a button is more like molding a 
door-knob than it is like making buttons by the combined operations 
of sawing, grinding, turning, and drilling, wherefore the molding of 
buttons should be classified in a general plastic art rather than in a 
special button-making art, yet the making of buttons by a plurality 
of different kinds of operations can be placed only in a class based 
upon the product, to wit, button-making. Since, therefore, the com- 
bination of many different operations for the production of a specific 
article can not be classified on the basis of any single function, it must 
be classified on the basis of product. Thus by selecting essential 
function as a basis when possible, and resulting effect when the 
functional basis is not possible, one may approximate to the correct 
classification described by Herbert Spencer as foUows: ^^A true classi- 
fication includes in each class those objects that have more charac- 
teristics in common with one another than any of them have with 
objects excluded from the class." ^ 

So it is deemed better to classify in accordance with the function 
or effect it is known a means must perform or accomplish than in 
accordance with the ohject with respect to which an act or acts are 
directed or in accordance with some effect which may or may not 
result. 

Structure as a basis. — The phrase ''structural classification" is fre- 
quently made use of. The application of the phrase to processes is 
manifestly absurd. The Patent Office never had a structural classifi- 
cation except in a limited sense. How could a machine, for example, 
be classified on structure, leaving out of consideration its function 

> Classification of the Sciences. 



CLASSIFICATION OF PATENTS. 15 

and the effect of its normal operation? In the refinements of sub- 
division, however, it becomes frequently desirable to form minor 
subdivisions on structural differences. And it may also be that 
instruments will be presented for classification that are of such 
general utility as to baffle the efforts of the intellect to attain to the 
fmdamental and necessary function, in which case a structure- 
defined class may best suit the needs of classification. 

As between a classification based upon structure and one based 
upon utility, the choice has been for the latter, without prejudice, 
however, to instances that may arise in favor of the former. 

The subject of structural classification will be dropped with a 
quotation from the original pamphlet "Plan of Classification," etc. 
(p. 5): "A purely 'structurar classification is almost impossible on 
account of the infinite variety of mechanical combinations, and to 
attempt it would probably result in utter confusion, for the classes 
could not be defined, and the classification would be a mere digest of 
mechanical elements having no community of function." 

DIVISION AND ARRANGEMENT. 

Having divided the aggregate of things to be classified into a large 
number of groups on a satisfactory basis, a most useful work will have 
been accomplished and the purpose of a classification to assemble 
the things most nearly alike and separate them from other things will 
have been partially achieved. Unless these numerous groups are 
arranged in some definite understandable relation to each other, or are 
placed in definite known positions where they can be found, the mere 
formation of the groups, on however good a basis, is not a complete 
classification. Furthermore, unless the position of each group with 
respect to those other groups that resemble it in whole or in part is 
made known, he who wishes to find other related matter must seek 
aimlessly with no assurance that his quest will end until the whole 
series shall have been investigated. Each classified group is meta- 
phorically a pigeonhole to contain similar material. If the pigeon- 
holes are properly labeled, one can ultimately locate those that contain 
the matter he is seeking if he knows the name that has been applied to 
it. If the pigeonholes are arranged in alphabetical order, for example, 
he may find all related material, provided tie Jcnoivs the name of every 
related group of material, even though very similar things may bear 
names as far apart as A and Z. But if all things were so placed that, 
adjacent and in certain fixed relation to each pigeonhole, other related 
matter could be found, the resemblances lessening in proportion to 
the separation, and if the entire area of pigeonholes were divided, 
and certain areas assigned to certain kinds of things defined in general 
terms, guessing the location of and desultory search for things that 
may have different names, but yet be very much alike, would be less- 



16 CLASSIFICATION OF PATENTS. 

ened and all cognate material be bunched. A second vital factor of a 
system of classification, therefore, is the arrangement of the groups. 

Infinitude of possible combinations. — There are now over 1,125,000 
United States patents, each presumptively covering a creation of the 
useful arts that is different from every other. Most of these patents 
also disclose a plurality of elements or acts. Each of these patented 
means is potentially an element of a more complex combination that 
may be patented. When one considers merely the number of forms 
of energy, the number of known substances and known mechanical 
elements, and attempts to figure possible combinations and permuta- 
tions, it becomes apparent that the size of the numbers resulting is 
incomprehensible. Consider the possibilities of combination also of 
the enormously varied disclosures of patents. Calculations of the 
possible combinations and permutations of a small number of objects 
are familiar. Different combinations of the letters of the alphabet 
are sufficient to record the sum of human knowledge in many lan- 
guages. With substantially two octaves of the diatonic scale the 
world's melodies have ,been sounded, nor do any doubt that our 
successors will thrill to airs that we have never heard. "Thirty 
metals may be combined into 435 binary alloys, 4,060 ternary alloys, 
27,405 quarternary alloys" (J.evons). This does not take into con- 
sideration differences in proportion that figure so largely in results in 
the arts of substance-making. The total number of possible allo3^s 
of the known metals is incomprehensible. A moment's thought 
respecting the numbers of the means of the useful arts will alleviate 
any fears that the possibilities of invention are near the limit and 
will give food for further thought to all concerned with this attempt 
to classify the useful arts to the point of refinement necessary to 
enable this office to pass judgment with reasonable speed and accuracy 
upon the approximately 75,000 applications filed each year. 

Division and arrangement in the natural sciences. — Some of the 
natural sciences are said to be in what is known as the classificatory 
stage of development. In some sciences the subject of classification 
has been predominant and these furnish excellent examples of scien- 
tific classification. 

The much-admired classifications of zoology, botany, and miner- 
alogy are among the best available models of logical division,^ sys- 
tematic and analytical arrangement. The most casual consideration 
of these classifications, however, renders apparent the relative sim- 
plicity of the task of classifying natural objects differentiated by 
fixed natural laws as compared with the task of classifying the 
products of the creative and imaginative faculties as applied to the 
useful arts. The chimera and other animal monsters occur only as 

» Lo^cal division is the process by which the species of which a genus is composed arc distinguished and 
set apart. T'hysical division or partition is the process by which the parts of any object are distinguished 
anl set apart. Metaphysical division is the process by which the qualities of a thing are segregated and 
set apart in thought. 



CLASSIFICATION OF PATENTS. 17 

figments of the mind. Zoological classification does not have to 
classify combinations of birds, fishes, reptiles, and mammals, nor 
does it deal in the way of classification with the parts of animals^ 
nor is the question of absolute numbers of instances a matter of 
moment to such a classification, all of the members of a species being 
alike for classification purposes. But any instrument of the useful 
arts may be combined with some other, any part with some other 
part. Organizations may be parts of some other organizations, or 
even mutually parts of each other, as, for example, a pump may be a. 
part of a lubricator, or a lubricator may be a part of a pump. Some 
parts are peculiar to one instrument, some are common to many. 
Every member of a species differs from, every other member. Added 
to this, the intellectual differences between the persons who present 
the applications for patent, the differences in their generalizing 
powers, the relatively broad and narrow views of two or more per- 
sons presenting the same invention (variations not indulged in by 
nature) complicate the problem of classifying the useful arts. 

Difficulty of entitling a subclass corresponding to every combination. — 
In any main class or group of the useful arts there are always a 
number of characteristics that it may be desirable to take note of in 
subdivision titles. A moment's thought shows the impossibility of 
taking care of any large number of combined characteristics so as to 
provide exactly for each combination, for the reason that the limita- 
tions of space and of the perceptive faculties forbid. For a simple 
illustration, the imaginary classification of books for use by a book- 
seller may be recurred to. The dealer, it may be assumed, has books 
on (1) four different subjects, history, science, art, and fiction, (2) 
each printed in four languages, English, German, French, Spanish, 

(3) in four different sizes of page, folio, quarto, octavo, duodecimo, 

(4) bound in four materials, leather, rawhide, cloth, paper. Here 
are four main characteristics, each in four varieties. A customer is 
likely to ask for Ivanhoe in English, octavo, bound in leather. Now 
if the bookseller had sought to arrange the books into one class ac- 
cording to subject matter, into another according to language, an- 
other according to size, another according to binding, he would have 
fallen into confusion, because his classes would be formed on different 
principles or bases and overlap. Some histories will be in French, 
some will have octavo pages, and some cloth bindings. But if he 
divides first on the basis of subject matter, then each subject matter 
into language, each language book into sizes, each size into material 
of binding, he can immediately place his hand on a class wherein the 
book will be if he has it; but this classification, based on four dif- 
ferent characteristics and four varieties of each, has necessitated the 
formation of 256 classes or divisions, and if five characteristics were 
provided for, 1,024 divisions would be required. 

102807—17 3 



18 CLASSIFICATION OF PATENTS. 

Adapting the illustration of the books to a patent office classi- 
fication: If it were possible to view these characteristics as patentable 
in combmations of all or in any combinations less than all, and also 
as separate characteristics, 16 divisions additional to the 256 for 
each independent characteristic would have to be provided, as well 
as other divisions for combinations of less than the whole, in order 
to make the classification absolutely indicative of every feature, 
and the number of divisions would be enormous. In such a classi- 
fication, after the proper division had been located, the search 
would be nothing, the difficulty would be to find the appropriate 
class. 

Expedients to reduce the number oj subdivisions. — Fortunately most 
people carry on their mental processes in accordance with certain 
uniformities. Under this uniformity of thought no patentable 
relationship may be alleged between a quarto volume and the subject 
of history or between a leather binding and the German language; 
wherefore 4 classes of coordinate value, based on the 4 characteristics, 
each divided into 4 subclasses, 16 divisions in all, may serve the 
purpose of a Patent Office search. But if, as sometimes happens, 
a patentable relationship had been assumed and admitted between 
a leather binding and any of the languages, or any of the subjects, or 
between any two or more of those different characteristics, provision 
could be made for such combinations by the following expedients: 

(1) Arrange the characteristics, in the order of relative signifi- 
cance or importance for the purpose in view, in four groups, giving 
each group the characteristic title. Under each title arrange the 
varieties in a similar relation as foUows in either (1) or (2): 



(1) 




(2) 


CI. X.— Books. 


CI. X.- 


—Books. 


0. Miscellaneous. 


1. 


Su ject-matter- 


0.5 Su^ ject-matter— 


2. 


History. 


1. History. 


3. 


Science. 


2. Science. 


4. 


Art. 


3. Art. 


5. 


Fiction. 


4. Fiction. 


6. 


Language — 


4. 5. Language — 


7. 


English. 


5. English. 


8. 


German. 


6. German. 


9. 


French. 


7. French. 


10. 


Spanish. 


8. Spanish. 


11. 


Size- 


8.5 Size— 


12. 


Folio. 


9. Folio. 


13. 


Quarto. 


10. Quarto. 


14. 


Octavo. 


11. Octavo. 


15. 


Duodecimo. 


12. Duodecimo. 


16. 


Binding — 


12.5 Binding material— 


17. 


Leather. 


IS. Leather. 


18. 


Rawliide. 


14. Rawhide. 


19. 


Cloth. 


15. Cloth. 


20. 


Paper. 


16. Paper. 


. 





CLASSIFICATION OF PATENTS. 19 

Subject-matter, assumed to be the most important characteristic, 
is placed first. Any exhibit of mere material for binding, mere size, 
mere language, or mere subject-matter, would fall into the corre- 
spondingh^ entitled group. If, however, a book on history in Ger- 
man or a history in red leather, etc., were to be classified, it would 
lo€> placed in subclass ''History" in the subject-matter group, and a 
French book in green cloth would be placed in subclass ''French'^ in 
the language group. That is, combinations of any characteristic with 
any one or more other characteristics may be placed in the group 
for that characteristic deemed the most significant and which is 
highest in the schedule. Again, by assigning a number to each 
generic title, each such title becomes thereby the miscellaneous group 
for varieties other than those indented under it, as well as for all 
varieties associating any characteristic with one or more of those 
standing lower down. Thus, a book of poems would belong in 
subclass ''Subject-matter" and a 16mo volume bound with purple 
celluloid covers would belong in subclass ''Size." So, by giving 
meaning to relative position, exhaustive arrangement is sought to 
loe provided in a reasonable number of groups. To provide for other 
features that may be presented in future, an additional miscella- 
neous group may be added at the top (1), or the class title (2) might 
be deemed to" represent the unclassified residue and a depository for 
future matter not specifically provided for. 

(2) If the number of instances of association of subject-matter and 
l)inding materials, language and size, etc., are numerous, additional 
groups might be placed above the groups having the names of the 
characteristics, the fact of the existence of these groups indicating 
that the characteristic groups are for single characteristics only and 
do not include books having several different ones. In such case the 
schedule might be headed by a miscellaneous group, having either the 
title "Miscellaneous" or the title of the class, to receive associated 
characteristics not provided for by specific titles, immediately fol- 
lowed by subclasses for the particular associations found to be most 
nimaerous, as follows: 

Miscellaneous. 

Su\ject-matter and language. 

Subject-matter and binding material. 

Su' ject-matter. 

Language. 

Size. 

Binding material. 

To illustrate further, selecting for the purpose a mass ot objects 
presenting problems more nearly like those presented to the office in 
questions of patentabihty, let it be assumed that one is to classify 
the objects in a heap of metal scrap. 

On looking over the material of the heap it is noticed that there 
are a large number of metal balls; some have holes through them, 



20 CLASSIFICATION OF PATENTS. 

some are hollow, some are smooth on the outside, and some are 
hollow, smooth, and perforated, but they are all nevertheless balls^ 
and accordingly all balls can be separated out and placed in a heap 
by themselves. Next, the presence of bars in the general mass is 
observed, some long, some short, some straight, some twisted, some 
of round stock, some of square stock, etc. These may be gathered 
together and placed in a separate pile at the left of the balls. It is 
further observed that there are many differently shaped annular 
bodies in the heap resembling generally the single links of a chain, 
some circular, some elliptical, some twisted, some made of round 
stock, some of square stock, etc. They are all nevertheless annular 
bodies; these may be placed in a separate pile at the left of the bars. 

Now, in the remnant of the original heap, a sufficient number of 
similar single elements does not remain from which to make a smaller 
pile of elements. Different combinations of links, balls, and bars 
are, however, observed in the remaining heap. Some are combi- 
nations of links, some combinations of a ball and link, some of a bar 
and link, and some of a bar, link, and ball. These different combi- 
nations may be separated out in the order named and placed in 
separate piles. After all these things have been removed, there is. 
left in the original heap a number of odds and ends or miscellaneous 
metal objects. 

These several groups may now be arranged in the inverse order in 
which (in the particular illustration adopted) they have been re- 
moved, thus: 

1. Miscellaneous (remnants of the original heap of scrap). 

2. Combined bar, link, and bail, 

3. Combined bar and link 

4. Combined bar and ball. 

5. Combined link and ball. 

6. Chains 

7. Links. 

8. Bars 

9. Balls 

Knowing that objects of metal scrap not covered by the specific 

titles will be found in the miscellaneous group, and that the more 

complex specifically-named things are to be found first after the 

miscellaneous or at the left of the row of piles of materials thus 

separated and arranged, and the more simple things and parts farther 

to the right, the particular piles to resort to for the things wanted 

may be definitely determined. The same processes may be applied 

to each of the piles. Thus, balls, in the above illustration, may be 

divided into — 

Balls— 

10. Hollow perforated. 

11. Hollow grooved. 

12. Hollow. ' 

13. Perforated. 
14 Grooved. 



CLASSIFICATIOX OF PATENTS. 21 

Again, the same processes may be applied to a mass of more 
diversified junk, of which the metal scrap may form one pile, rags 
another, old bricks another, old timber another, and, still another, 
timber having metal-straps, bolts, nails, etc., connected with it. 

Superiority and inferiority. — In the arrangement of subclasses in a 
class, those groups that are related to each other as wholes and parts 
are arranged so that the wholes shall stand before the parts, and so 
that subclasses defined by effect or by special use shall stand before 
those defined by function or general use. For example, in the scrap 
illustration above, assuming the titles to be in a printed arrangement, 
^'chains" precedes ''links," which may be parts of chains, and if it 
had been desired to separate animal-drags, for instance, from the 
scrap, some animal-drags being particular adaptations of a bar, Hnks, 
and ball, the group of animal-drags should precede ''Bar, link, and 
ball. " The words "superior" and ' 'inferior" have been used to indi- 
cate this relationship. A class or subclass defined to receive a certain 
combination is superior to one defined to receive an element or a 
combination that is a part of that certain combination. A class or 
subclass defined to receive means for making a particular product, as 
an electric lamp, is superior to a class or subclass designed to perform 
u general function, as piunping air from a container. And whenever 
a question of assignment of a patent or application that contains 
matters of two or more groups bearing that relation is raised, the 
^'superior" group is selected to receive it. 

Further, in those instances in which groups are formed on different 
bases or different characteristics, not comparable with each other, 
and a patent is presented having matter falling in each group, that 
group which is highest in position is preferred in those instances 
where separate provision for means having both characteristics has 
not been made. 

In cases of necessity, as where a combination is presented for 
which no class has been definitely provided, but classes exist int<D 
which the several parts would fall if separately claimed, the same 
practice that obtains in similar situations with respect to two or 
more subclasses of a class may be followed with respect to two or 
more classes and the patent placed in that class which, in accordance 
with above-stated principles, should be deemed the "superior." 

Definite positional relationship of subdivisions. — In the metal scrap 
example, above, division has been effected on the one basis of form 
or contour. If it had been desired to separate also on material, for 
example, if it were deemed important to locate aU brass scrap, each 
of the groups based upon form could be divided into one of brass and 
one not brass, or the entire heap could be divided into brass and not 
brass, and under the heading "brass" could be indented the various 
articles made of brass, and under "not brass" the various articles not 



22 CLASSIFICATION OF PATENTS. 

made of brass, and this would double the number of divisions. If 
also it were desired to separate the lead articles in the same manner 
the number of classes would be tripled. But, as in the book illus- 
tration, it may be impracticable thus to multiply subdivisions, and 
the basis ''form" having been selected as oi first-rank importance, all 
divisions based upon form should be completed and kept together. 
Then, ''material;" having been selected as of second-rank importance, 
should be carried out with respect to all objects in which form is non- 
essential. If enough brass balls were found to render it advisable to 
make a subdivision of them, they should be assembled into a sub- 
class indented under ''balls" and not into a subclass indented under 
"brass." Having selected one basis as ^primary, it should never 
subsequently be made secondary or vice versa. Some such restriction 
on modes of division appears salutary in a system of divisions designed 
to definitely limit search. The arrangement herein sought to be 
explained is susceptible of use to limit aU searches for a simple defi- 
nitely stated invention to a subclass properly entitled to receive it 
or those indented under it, and to those subclasses above, which 
may include it as a part of an organization or specialized means. 

As between coordinate groups divided on the same basis, there is 
no question of superiority and inferiority. The terms "superior" and 
"inferior" are useful in questions of relationship between combina- 
tions and subcombinations or elements thereof, and between groups 
founded on effect or product and those founded on simple function. 
The mere difference in complexity of mutually exclusive coordinate 
groups involves no relationship of superiority or inferiority. A sub- 
class to receive a screw-cutting lathe is superior to a subclass to 
receive a lathe-headstock, a locomotive class is superior to a class to 
receive steam-engines, for the reason that the lathe is a whole of 
which the headstock is a part, and the locomotive is an organization 
of which the engine is an element. But the headstock subclass is 
not superior necessarily to the tailstock subclass simply because the 
headstock is commonly more complex than the tailstock. Yet arbi- 
trary preference for classification in the headstock subclass may be 
established by position where an application or a patent contains, 
claims for both. 

Thus in a class that is founded on a weU-chosen basis that brings 
together things bearing close resemblances to each other, aU types 
that contain the elements essential to produce a complete practically 
operative means wiU be found in subclasses that have a position 
somewhere between the beginning and end of the list of subclasses of 
the class. Those that add features of elaboration of the essential 
types and those that are highly specialized to some particular pur- 
pose within the definition of the class will stand above the essential 



CLASSIFICATION OF PATENTS. 23 

type subclasses, while those subclasses for parts and details will 
stand below those for the essential types. 

Indented schedules. — In an indented schedule aU subclasses in the 
first colunui reading from the left are species to the genus repre- 
sented by the class title.^ All subclasses indented under another sub- 
class are species to the genus represented by the subclass under 
which they are indented. If a title has no number, it represents 
merely a subject-mattefr to be divided, a genus, — having no represent- 
atives except in the species imder it. If a subclass having a generic 
title has a number, it not only represents a subject-matter to be 
divided into species but also all other species not falling within the 
titles indented. Although these relative positions might imply that 
only proximate species are indented one place, yet mechanical diffi- 
culties render it impracticable to so arrange that all species shall be 
indented under their proximate genera. 

Indention properly carried out has a tendency to prevent in the 
process of logical division the logical fault of proceeding from a high 
or broad genus to a low or narrow species. This latter fault may 
inadvertently separate things that belong together. If, for example^, 
it were desired to divide balls in the stated illustration according to 
material, an immediate division of balls into aluminum, zinc, glass,, 
ivory, rubber, would be less useful than to divide into mineral 
materials and nonmineral materials as follows : 

Balls- 
Mineral — 

Nomnetallic — 

Glass. 

Metallic — 

" Aluminum. 

Zinc. 

Nonmineral — 

Vegetable^ 

Rubber. 
Animal — 
Ivory. 

1 Any class of objects may be called a " genus " if it be regarded as made up of two or more different kinds 
of objects or of two or more species. "Motors" is a genus when the class "Motors" is considered as divided 
into electric motors and nonelectric motors, or electric motors, spring motors, weight motors, current motors, 
fluid pressure motors, etc. A genus is more extensive than any of its species but less intensive. 

A "species" is any class that is regarded as forming a part of the next larger class, "electric motors" 
being a species of "motors" and "motors" being a species of "energy transformers." A species is more 
intensive than the genus to which it belongs but less extensive. 

Every species may be a genus to another species until no further subdivisions can be made. This last 
indivisible species is termed the infima species. Every genus may be a species to another genus imtii a 
point is reached where no further generalization may be made or the summum genus is attained. In the 
Patent OflBce classification of the useful arts, the summum genus is useful arts. The summum genus: 
of the plastic arts would be plastics. The infim,a species in the useful arts evidently never can be attained'.. 

"Proximate species" and "proximate genus" indicate, respectively, those species that are divided front 
a genus without intermediate genera, and those genera from which the species are directly divided. Motors, 
and not energy transformers, is the proximate genus to the species, fluid motors, electric motors, etc., while- 
fluid motors, electric motors, etc., and not steam engines, alternating current motors, etc., are proximate- 
species to motors. 



24 CLASSIFICATION OF PATENTS. 

However, it is evident that indention carried to its full extent, 
useful as it is in keeping analogous things together, would make the 
printing of schedules complex and unwieldy. Nevertheless, in the 
generalizing process necessary in logical division and arrangement, 
the div^isions of species should always be mentally indented, as it were, 
imder their proximate genera. Thus, under a genus unnamed may be 
arranged several species in juxtaposition, without actually printing 
the name of the genus, so that the schedule above may read: 

Balls- 
Glass. 
Aluminum. 
Zinc. 
Rubber. 
Ivory. 

In an arrangement printed in idea-order, though relegating the 
genera mineral, nonmetallic, metallic, nonmineral, vegetable, animal, 
to the mind unaided by printed words, the different species of the 
same genus may be kept together except that species for which no 
title has been provided must go back to the subclass under which the 
named species are indented. Thus the arrangement above necessi- 
tates placing in subdivision " Balls" all copper balls, whereas indention 
under proximate genus ^^ metal" would have brought all metal balls 
together. In a finely divided classification, printing of titles for all 
genera is not practicable ; hence great care ought to be directed toward 
grouping species according to the principles of arrangement herein 
outlined, noting that whenever a change of basis is made, a new genus 
is implied, and that subclasses for all other species of the same genus, 
under whatever name, must be brought into juxtaposition as if 
indented under the implied genus. ^ 

Bifurcate division. — Most discussions of classification make refer- 
ence to the so-called bifurcate scheme of division as the only one by 
which exhaustive division can be surely achieved. This is commonly 
illustrated by the ancient tree of Porphyry. By this method any 
subject it is desired to subdivide is first divided by writing the name 
of one selected species at one branch and writing at the other branch 
the name of the same species prefixed by "Not." Thus the Agassiz 
classification of living beings divides them first into sensible and not 

1 In the Manual of Classification of the U.S. Patent Office the arrangement of subclasses has always 
"been alphabetical, although in the Supplement containing definitions of revised classes the arrangement 
is numerical. If the latter schedule of "Balls" in the text had been printed in aljjhabetical order, it is 
apparent that the species "Aluminum" and "Zinc" of the genus Metal would be as widely separated as 
possible. In the former schedule of "Balls," in which the genus Metal is printed, "Aluminum" and 
*'Zinc" come together. It is apparent that in an alphabetical arrangement allied species can not be kept 
together without printing every proximate genus. This fact, among others, indicates the advisability 
of abandoning the alphabetical arrangement in the classification manual and adopting the idea arrange- 
ment in the schedules of revised classes, supplemented by a consolidated alphabetical index of sU sub- 
classes. 



CLASSIFICATION OF PATENTS. 25 

sensible (plants). A botanical classification divides plants into 
flowering and not flowering. A zoological classification divides 
animals into vertebrate and not vertebrate. By continuing the 
process of division in the same manner, the division is obviously 
exhaustive of the subject, there being always a negative subdivision 
to receive any subsequently created or discovered species. Although 
bifurcate division has been ridiculed by some, it is agreed by highest 
authority that it is the only plan of division by which one can be 
sure to have a consistent place for everything, or by which one can 
be certain that the divisions are mutually exclusive. It can be 
demonstrated that a classification schedule in which the relation of 
genera and species is shown by indentions, if correctly formed on 
the principles now sought to be applied in the revision of the Patent 
Office classification, is susceptible of conversion into a tree of 
Porphyry, while unlike the latter it is compact and wieldy. 

Utility of arrangement according to rese7nblanc( s . — The expedient of 
indicating kinds of relationship between several equally indented 
divisions by relative position has the following utility: 

(1) A uniform rule is provided, applicable to all classes, for placing 
inventions that bear the relation of whole to part in subdivisions before 
those that bear the relation of a part to that whole, and those that are 
defined by a particular effect, product, material, or use before those 
that are defined by a function or an operation applicable generally 
to various effects, products, materials, or uses; whereby that portion 
of the schedule in which any invention belonging to any particular 
class should be found may be approached whether or not the investi- 
gator knows the name of the object sought for or the title of the 
appropriate subdivision. 

(2) The substantial impossibility of dividing many branches of 
the useful arts exhaustively into a reasonable number of mutually 
exclusive or non-overlapping subclasses is compensated for; so that 
when the classifier or the searcher has an invention to place or to 
find including two or more different kinds of characteristics, for each 
of which a subdivision is pr£>vided, but no subdivision for the plural 
characteristics, it will be known that the invention should be in the 
subclass for that characteristic which stands before the subclass for 
the other characteristic. 

(3) It compensates for omission of some generic titles that if written 
in the indented schedule would lengthen specific titles to a cumber- 
some extent. 

(4) It provides a rule for cross-referencing where several inven- 
tions are claimed bearing to each other any of the relationships 
indicated above, cross-referencing being necessary in one direction 
only where the matter illustrated is coextensive with the matter 
claimed. 



26 CLASSIFICATION OF PATENTS. 

(5) It definitely limits the field of search for any unitary invention 
in any class so arranged, as no patented invention having the limita- 
tions imposed by a unitary claim should be found in any subclass 
below the subclass properly defined to receive it or those indented 
under it. Parts of such inventions may be found below or following 
this subclass in the same class if these parts are within the class 
definition, or elsewhere in the useful arts if not within that defini- 
tion. The unitary invention may be found in the subclass limited to 
it and certain subclasses arranged above or before it adapted to re- 
ceive organizations of which it may be a part. 

A complete system of arrangement should comprise (1) a display 
of the entire field of the useful arts in a manner to show the relation 
of the larger as well as of the smaller groups, — carrying the appro- 
priate relationship as far as possible from the highest genera to the 
lowest species, the arrangement being such as would bring materials 
most nearly alike into closest propinquity regardless of the names 
they may be called by. (2) Supplementary to this classification 
arrangement by ideas there should be an alphabetical index of sub- 
class titles, appropriately cross indexed, and additional titles of 
various technical and trade names of things classified under subclass 
titles. 

DEFINITION. 

DeS^nition is indispensable in any classification and is very difficult. 
Every class must be defined and all of the groups under it. After 
definitions have been made and printed, they are sometimes found 
inadequate and must be supplemented by the definitions of other 
classes. This is unavoidable while the complete material remains 
unexplored. Definition in the strict logical sense is not to be expected, 
nor is it necessary. It is commonly sufficient if an explanation or 
comparison be made sufficient to direct the mind to the character of 
the contents of the group and indicate its limitations. Hitherto four 
of the five predicables of ancient logic have been mentioned, to wit, 
genus, species, property, and accident. In connection with definition, 
the fifth predicable, difference, is useful. To define a class, it is suffi- 
cient, generally, for the purposes of office classification, to state a 
peculiar property (not an accident) of the objects included in the 
class; and to define a species under the class it is sufficient to state 
the name of the class plus the difference — i. e., with the addition of the 
limitations that characterize the species.^ This procedure in defini- 
tion is susceptible of application from the highest genus to the lowest 
spedes. It is advisable to define the means included within a title 
without any introductory words, such as ''this subclass includes 

1 A species contains all the qualities of the genus and more. These additional qualities form the "differ- 
ence." The electric motor has the qualities that are common to motors and is differentiated by reason of 
the fact that ele:tric energy is thereby converted to mechanical motion. 



CLASSIFICATION- OF PATENTS. 27 

inventions relating to," etc., treating the subclass for definition pur- 
poses as if it were a collection of concrete things, in the same manner 
as in a dictionary definition. 

CROSS-REFERENCES AND SEARCH-NOTES.^ 

If patents were in all respects like material objects, cross-references 
and search-notes would not be necessary. Nails, screws, locks, 
hinges, and boxes are distinct things susceptible of definite separa- 
tion and classification. Even though nails, screws, locks, and hinges 
form part of the box, the box is still a box, not a nail, screw, hinge, or 
lock. For the needs of the Patent Office classification, however, 
although a patent for a box must be classified with boxes, yet if a 
peculiar nail, screw, lock, or hinge is claimed in the same patent with 
the box, or even if any one of these customary accessories of boxes is 
illustrated, it may be necessar}^ to provide copies of the patent for the 
box in each of the several classes provided for nails, screws, locks, 
or hinges. 

Inasmuch as every relatively complex thing is made up of relatively 
simple things, it is obvious that all disclosures can not be cross- 
referenced. Any attempt to calculate the number of cross-references 
to be supplied if aU disclosures of the subjects of invention were to be 
cross-referenced would show the number to be incalculable. It is 
necessary, therefore, to leave to the judgment of the classifier the 
propriety of cross-referencing unclaimed disclosures. 

Should a patent contain a number of claims defining a number of 
dift'erently classifiable inventions, complete cross-referencing from 
the class in which the classification is made original into the other 
appropriate classes or subclasses should be effected, unless cross- 
search notes or arrangement of subclasses with appropriate titles may 
be substituted to advantage. 

Cross-references are made, as a rule, from combination class to 
element class, but never or very rarely from the element class to the 
combination class in which it may be used. Thus cross-referencing 
should normally be downward in a schedule of subclasses. Search 
notes indicate ^'superior" classes or subclasses parallel or otherwise 
related classes and subclasses, or those classes and subclasses in 

1 Classification of a patent is said to be "original " in the class and subclass which receives the most inten- 
sive claimed disclosure, and in which the patent is indexed in the official classification indexes. " Original 
classification" is referred to as opposed to "classification by cross-reference." 

A "cross-reference" is a copy of a patent placed in a subclass other than that in which the classification 
is made original, in order to make available for search inventions disclosed therein and additional to that 
by which the patent has been diagnosed and classified. 

A "digest cross-reference" is a cross-reference formed from abstracts or extracts from a patent consisting 
of illustration and text cut from a photolithograph of a patent and mounted. 

A "search-card" is a sheet of the size of a photolithograph of a patent placed with the photolithographs 
of patents forming a subclass in the examining division and public search room, and containing sugges- 
tions for further search, and on the copy for the search room, a definition of the subclass. 

"Search notes" are addenda to class and subclass definitions comparing other classes and subclasses 
with the one defined and giving directions for search when necessary to prosecute search beyond the defined 
class or subclass. 



28 CLASSiriCATION OF PATENTS. 

which analogous structures having different purposes but adapted to 
answer broad claims may be found. 

By arbitrary rules of arrangement such as have been referred to in 
the section dealing with division and arrangement, a search may 
ordinarily be definitely limited to a certain number of subclasses, 
even where cross-references are not made. In such arrangement any 
given patent, if it he directed to one invention, may be searched in the 
subclass within which the definition places it or subclasses indented 
under it, and in certain subclasses above, whose titles will indicate 
that the invention might be included as a part of the matter defined 
to belong therein, but the identical thing would never have to be 
searched for in any subclass following and not indented thereunder. 

DIAGNOSIS TO DETERMINE CLASSIFICATION. 

Each patent and each application discloses one or more means of 
the useful arts (using the term ''means" to cover bath processes and 
instruments in the sense in which it is used by Prof. Robinson), 
almost always more than one, since most new means are combina- 
tions of mechanical elements or acts. In some patents and applica- 
tions the disclosure is coextensive with that which is claimed; in 
others there is matter disclosed but not claimed. The unclaimed 
disclosure may be as valuable as the claimed disclosure for purposes 
of anticipation, and the classification must provide for both. If the 
claimed disclosure belongs in one class and the unclaimed in others, 
the classifier must choose between two or more classes that one 
in which the patent or application shaU be classified and those into 
which it shall be cross-referenced. 

Claimed or unclaimed disclosure. — The claims of a patent are the 
statutory indices of that which the applicant believes to be new, 
they define an invention that has been searched by the Patent Office 
and no anticipation discovered for it. Future action must be based 
on inductions from past experience; none knows what the future 
lines of search will be; the only guides for future searches are the 
searches of the past; the evidence of past searches is the claims 
of patents; they trace the course of invention. Furthermore, a 
presumption of novelty attaches to the claimed matter; no such pre- 
sumption attaches to the unclaimed. The law requires every patent 
for improvement to show so much of the old as is necessary to explain 
the uses of the improvement. In practice much more than that is 
disclosed. Questions as to the proper placing of patents and cross- 
references would be diminished by the strict enforcement of Rule 36 
of the Rules of Practice requiring that the description and the draw- 
ings, as well as the claims, be confined to the specific improvement 
and such parts as necessarily cooperate with it. In any event both 



CLASSIFICATION OF PATENTS. 29 

the claimed disclosure and that which is unclaimed must be taken 
care of, one by cross-reference, and the disclosure selected for cross- 
reference is that to which no presumption of novelty attaches. 

This practice of placing patents by the claimed disclosure is some- 
times misunderstood. Its chief application is in determining classifi- 
cation in case of disclosures involving a plurality of main classes. 
Furthermore, the mere letter of the rule is not to be applied in 
preference to its spirit. Difference in scope of claims does not cause 
different classification. Subcombinations claimed may be placed 
with the combinations, and in subordinate type subclasses patents 
must be placed sometimes by claimed and sometimes by not-claimed 
disclosures . 

Diagnosis of pending applications. — What has been said relates to 
patents. The bearing of the practice of adopting the claimed dis- 
closure as the basis of assignemnt of applications for examination 
has also to be considered. 

Two pending applications claiming the same means very commonly 
differ in the kind and extent of disclosure. One application may 
disclose several inventions. Which of the several disclosures shall be 
selected as the mark by which to place the application ? For instance, 
the typical wire-nail machine has a wire-feeding mechanism,' a shear- 
ing mechanism, an upsetting (forging) mechanism, side-serrating 
mechanism, and pointing mechanism; it m_ay also have a counting 
mechanism, a packaging mechanism, an electric motor on its frame 
for furnishing power; and, in addition, numerous power-transmitting 
and other machine parts, such as bearings, oil-cups, safety appliances, 
etc. The applicant may have made a complete new organization of 
nail-machine and may seek a patent for the total combination. 
He may have invented a new shearing mechaninsm and have chosen 
to show it thus elaborately in the place of use he had in mind, or he 
may have designed a new counter or a new oil-cup or a new power 
transmission, or even a new motor, and have given his invention 
this elaborate setting. The shears, the counter, the oil-cup, the 
power transmission, and the motor are separately classifiable in 
widely separated classes. How shall the application be diagnosed 
for determining its place in the office classification ? When the -speci- 
fication and drawing disclose (as most of them do) several subjects 
matter of invention, though claiming only one, which of those several 
subjects matter shall control the classification? 

The most natural procedure, at first thought, would be to classify 
on the totality of the showing, in which case the application for the 
nail-machine, supposed above, would be assigned to nail-makmg. 
But imagine the invention claimed by an applicant to be the counter. 
Then the examiner in charge of nail-making would have to search the 
class of registers with which he is not familiar. Suppose appli- 



30 CLASSIFICATION OF PATENTS. 

cant No. 2 files an application for the same counter which he illus- 
trates and describes in connection with a bottle-filling machine, and 
that, classifying on the totality of the showing, this goes to the 
division that has the class of packaging liquids. Now both the 
examiners in charge of bottle-fiUing and nail-making, knowing that 
counters are classified in registers, search the class of registers and 
also the pending applications in registers. After these examiners 
have made their searches, suppose applicant No. 3 files an applica- 
tion for the same counter, which he says may be used for counting 
small articles produced by automatic machines. Perhaps he shows 
the counter attached to a piece of conventional mechanism repre- 
senting any manufacturing machine, m.entioning, say, a cigarette or 
pill or cartridge-making machine. It has not occurred to either the 
examiner of nail-making or the examiner of bottle-filling that the 
other might have any such application; nor does it occur to the 
examiner in charge of registers to search nail-making or bottle-filling. 
As the specification of the counter application mentions cigarette, 
pill, and cartridge-making machines to which the counter may be 
attached, the examiner in charge of registers may search those 
classes. Suppose that the counter |)roves to be new, and each of the 
three examiners allows a patent. Here now are three patents for 
the same thing. Of course, after allowance, the counter and all 
other disclosed inventions that give any suggestion of novelty are 
cross-referenced; but the primary purpose of a patent office classifica- 
tion (to aid in determining patentability) has failed in this instance. 

In the imagined situation respecting pending applications, without 
doubt diagnosis and classification upon the invention claimed is 
necessary to effect the purpose of the office classification. Cross- 
referencing after issue can not undo that which has been done. 

If no application save that of the nail-machine be pending, no 
duplication of patents occurs, but the labor of search is increased by 
reason of the unfamiliarity of the examiner with the inventions he 
Las to search. After the patent is allowed he may find the entire 
•combination of the nail-machine without the counter disclosed in a 
patent for a nail-making machine, so that as a nail-making machine 
this new patent is of no value as a reference. Very probably all of 
the other inventions illustrated (except the counter) are also old in 
their respective classes; but the examiner of nail-making can not 
tell this without extensive searches in those classes, so he notes cross- 
references for them all. 

Difficulties due to varying ideas of claims. — Very troublesome ques- 
tions are constantly arising as to whether an invention should be 
classified in a combination class or an element class. The point will 
be illustrated by example: A describes ami illustrates an automobile 
having an internal-combustion motor and a friction-clutch in the 



CLASSIFICATIOX OF PATENTS. 31 

motor transmission-gear. He states that the clutch is in the usual 
relationship to the motor and gearing, but claims a new clutch for 
whatever it may be adapted. B discloses an internal-combustion 
motor said to be for automobiles with transmission-gearing and a 
friction-clutch and claims " in an internal-combustion motor a friction- 
clutch/' etc., specifying the form of the clutch. C makes the same 
disclosure, but claims ''an internal-combustion motor having a speci- 
fied clutch," while D, with the same disclosure, claims "the combina- 
tion with the internal-combustion engine of an automobile'" of a 
specified friction-clutch. E claims and illustrates only the friction- 
clutch. Should these be classified together ? If so, in what class ? 
Should a bearing composed of a specified alloy of copper, tin, and anti- 
mony, be classed as a bearing or as an alloy ? Should a house painted 
with a mixture of linseed oil, lead oxid, and barium sulphate go to 
buildings or coating compositions? A lamp-filament of titanium 
and zirconium with electric lamps or with alloys ? A building-block 
of cement, lime, sand, and carbormidum, with building-blocks or plas- 
tic compositions ? Whether these be diagnosed as combinations or as 
elements and compositions respectively, and classified accordingly, 
criticism will be aroused. The point in view is that although princi- 
ples of patentability must be considered in a classification designed 
as an instrument to aid in determining patentability, convenience 
and accuracy of search and avoidance of voluminous cross-referencing 
may necessitate some arbitrary rule of classification to meet various 
and changing theories applied to the drafting and allowance of claims. 
From the foregoing it will be evident that classification involves 
orderly logical processes of induction (supplemented by hypothesis), 
of definition and of deduction. After gathering a large number of 
facts generalizations are made from them and a hypothesis is found 
to be confirmed or modified by more extended research; the divisions 
are then defined; by correct diagnosis of other instances (as other 
patents) deductions may be drawn respecting the appropriate place 
for them in the classification. 

(C) RTJLES OF CLASSIFICATION. 

BASIS OF CLASSIFICATIOX. 

(1) The basis of subdivision and assemblage of the means of the 
^'useful arts'' in the Patent Office classification is ''art" within the 
meaning of "art" in section 4886, Revised Statutes. The direct, 
proximate or necessary art, operation or effect, rather than some ac- 
cidental and remote use or application, should be selected. " In all 
cases qualities or characteristics that persist through all accidental 
uses and that can be identified as permanent are to be preferred. 

(2) The operative, instrumental, or manipulative arts, including 
machines, tools, and manufacturing processes, should be classified 



32 CLASSIFICATION OF PATENTS. 

according to whether a single operation of one kind apphcable to 
various materials to be used for various purposes is carried out by 
the claimed means, or whether plural operations are performed^ 
which, combined, produce a special effect or special product. 

Example: An instrument performing a plurality of operations peculiar to shoe- 
manufacture would l:e classified on the 1 asis of shoemaking, 1 ecause that instru- 
ment would 1 e incapa^ le of other use, while an instrument peculiarly adapted to 
drive nails would he classified on the ' asis of nailing, whether for nailing shoe-heels 
or other o" jects, and a hammer would i e classified on the basis of its function as an 
impact tool even though descrf ed as for driving nails, and even into shoe-heels. 

(3) Structures (passive instruments) will, in general, be classified 
on the basis of structure, either of special or general application, the 
essential finictions and effects of static structures being resistive or 
the maintaining of forces in equilibrium. 

Example: A structure recognized as peculiar to barriers of the kind known ae 
fences would 1 :e classified in the special class of Fences, . ut posts, joints, ] eams, 
etc., recognized as having use in general luilding, even though descri' ed as used 
in fences, would \e classified in a more general ' uilding class, such as Wooden Build- 
ings or Metallic Building Structures. 

(4) Compositions of matter and manufactured or formed stock or 
materials will be classified in accordance with the inherent character 
of the substance or material where possible, otherwise according to 
special use. 

Example: A pure chemical is expected to be classified on the basis of its chemical 
structure and constituents, even though useful as a food, medicine, dyestuff, explo- 
sive, etc., and alloys on the basis of metallic composition, even though used for 
bearings, coins, tools, etc.; whereas a physical composition having no reason for 
existence except to function as a cleansing composition or a paint might have to be 
classified on the " asis of its function as a detergent or a coating composition, respec- 
tively. Also a ' imetallic layered foil, plate, or wire would ] e expected to \ e classi- 
fied as metal stock even though designed for use for dental filler, plowshare, or elec- 
tric conductor, and a woven textile fa ric as a fa ric even though descri ed as used 
for a filter or apron for a paper- making machine. 

DIVISION AND ARRANGEMENT. 

(5) The divisions or subclasses of a class should be made exhaus- 
tive, i. e., they should be susceptible of receiving any future invention 
that may fall within the scope of the class. The rule as usually 
phrased is: ''The constituent species must be equal, when added 
together, to the genus." Exhaustive division may be secured by 
maintaining always a residual or miscellaneous subclass. The mis- 
cellaneous subclass represents the remainder of the original undivided 
material undefined except as the class is defined and may be accurately 
treated as if it had the class title. 

(6) "The constituent species must exclude each other." That is, 
the divisions or subclasses must not overlap. (See exceptions in 
Rules 8 to 12.) 



CLASSIFICATION OF PATENTS. 



33 



Example: If a number of balls of several different materials, several different 
conformations, or constructions, several different colors, were to be divided into glass 
balls, hollow balls, and red balls, this rule would be violated, because some balls 
would be glass, hollow, and red. 

(7) ''The divisions must be founded on one principle or basis/' 
The application of this rule will generally form divisions that do not 
overlap. (See exceptions in Rules 8 to 12.) 

Example: If a number of balls of several different constructions, several different 
materials, and several different colors were to be classified so as to provide a place for 
each kind of characteristic, they should be diAdded first, for example, according to 
construction into hollow balls and solid balls, each of these according to materials 
into glass balls, rubber balls, metal balls, wooden balls, etc., and each of the latter 
into red balls, blue balls, green balls, etc. 

(8) When it is found that division into overlapping subclasses and 
on different characteristics is a lesser evil than an unwieldy number 
of subclasses that would otherwise result, then those subclasses based 
on characteristics deemed more important for purposes of search 
should precede in the list of subclasses those based upon character- 
istics deemed less important. (See Rule 6.) 

(9) In arrangement of subclasses or subdivisions the miscellaneous 
groups containing material not falling within any of the specifically 
entitled subclasses, should stand first; those subclasses defined by 
effect or special use should precede those defined by function or 
general use; those containing matter that is related to the matter of 
other subclasses as whole to part should precede those subclasses 
that contain the part; and those defined by a characteristic deemed 
more important or significant for search purposes should precede 
those defined by characteristics deemed less important. 

■ Whenever superior rank has been assigned to any selected character- 
istic by placing divisions based upon it in advance of divisions based 
upon other characteristics, this superiority should he maintiined 
throughout. 

Example: A partial schedule of Class 80 follows to illustrate the arrangement of 
subclasses : 

*" Class 80. — Metal Rolling. 

Tubes — Continued, 

13. Axial rolling. 

14. Segmental rolls. 

15. Skelping. 

16. Wheels and disks. 

17. Reworking. 

18. Concave and roll. 

19. Platen and roll. 

20. Platen rolling— 

21. Disk platens. 

22. Axial rolling — 

23. Pattern rolls. 



1. 


Miscellaneous. 


2. 


Heating and rolling. 


3. 


Cutting and rolling. 


4. 


Drawing and rolling 


5. 


Annular bodies. 


6. 


Screw tlireads — 


7. 


Concave and roll. 


8. 


Platen rolling- 


9. 


Dies. 


10. 


Rods and wires. 


11. 


Tubes- 


12. 


Idle rolls. 



34 CLASSIFICATION OF PATENTS. 



Clas^ 80. — Metal Rolling — Continued. 



1 



24. 


Die rolling — 


25. 


Oscillating rolls. 




Mills- 


32. 


Coiling. 


33. 


Work reversing. 


34. 


Three or more coacting rolls. 


35. 


Continuous — 


36. 


Inclined trains. 


41. 


Roll cooling and heating. 


42. 


Cooling beds. 



43. Feeding- 

44. Tables. 



55. Housings. 

56. Roll adjustments — 

57. Relief devices. 

58. Rolls— 

60. Processes — 
66. Flanged bars. 



In this schedule the miscellaneous subclass is numbered 1, then follow three sub- 
classes (2-4) of rolling plus another function, then four major subclasses (5-16) of 
rolling, merely, but applied to blanks of special form producing special products, 
then one special subclass (17) based upon a special class of material treated, then five 
subclasses (18-31) specialized in type and mode of operation, then general types of 
rolling mills (32-40), then various parts and accessories (41-59), then processes (60-66). 
This is the usual arrangement and is an exhaustive division for the art of metal rolling. 
Had there been miscellaneous subclasses for all combined operations of rolling plus 
some other function, a miscellaneous subclass for all mere rolling machines, either 
special or general, and a miscellaneous subclass for all parts and accessories, the 
requirements of exhaustive division would have been also satisfied. 

In the illustrative schedule, there being no miscellaneous subclass for means having 
combined functions of rolling and another, any patent having claims for the combi- 
nation of a means for rolling and a means for cooling would fall in subclass 1, Miscel- 
laneous. In that subclass would also fall all "Mills," such as for rolling spiral con- 
veyer-flights, the same not falling under any of the subclass 32-40, no miscellaneous 
subclass of "Mills" and no special article-rolling subclass having been provided; also 
all parts or accessories, such as a water-cooled screen, peculiarly adapted to rolling- 
mills, there being no existing subclass of screens therein and no miscellaneous subclass 
of parts. The arrangement of subclasses in Class 80 requires that the combination 
of a furnace and a rolling mill shall be placed in subclass 2, even if the combination 
be designed and adapted for rolling annular bodies (subclass 5) or tubes (subclass 11). 
Means special to rolling a tube between a concave and roll must be placed in subclass 
13 rather than in subclass 18. A work-reversing mill must be placed in subclass 33 
rather than in subclass 34 even though it have three or more coacting rolls. 

The rolling of "Screw-threads" having been given higher rank than a "Concave 
and roll" mechanism, any concave and roll mechanism limited for use in rolling 
screw-threads should be formed into a subclass indented under "Screw-threads" 
and not into a subclass "Screw-threads" indented under "Concave and roll." 

(10) Class schedules are arranged with certain subclasses appro- 
priately indented according to a commonly understood expedient. 
In a properly indented schedule subclasses in column at the extreme 
left are the main species (the proximate species) of the class. The 
titles and definitions of all subclasses proximate to the class (at 
extreme left) must be read with the title and definition of the class, 
as if indented under the class title one space to the right; so also 
with the titles and definitions of subclasses indented under other 
subclasses. If a title has no number (as in Class 80, ' 'Mills '' ) , it repre- 
sents merely a subject-matter to be divided, assumed to have no 



CLASSIFICATION OF PATENTS. 35 

representatives other than those in the species indented under it. 
If a title having indented species under it has a number, it not only 
represents a subject to be divided but also a subclass including all 
other species not falling within the indented titles. Indention does 
not indicate superiority or inferiority, but merely that the title and 
the definition of the indented subclass must be read with the title 
and definition of the subclass under which it is indented. A title 
selected in a scheme of subdivision to be of first importance and 
placed, therefore, in advance, should not thereafter be indented 
imder a title selected to be of secondary importance and, therefore, 
having a lower position. (See Rule 8.) 

(11) A group of material may be divided on several different bases. 
''Use" or ' 'purpose'' or ''object treated" may be adopted only 
when the ''use" or "purpose" or "object treated" stamps upon the 
invention such peculiarities of operation or construction as to limit 
the applicability of the invention to the use or purpose named. 
(See Basis of Classification, Rule 1.) A group based upon mode of 
operation also may be divided into subclasses (1) with a "functional" 
title, usually participial in form, and adapted therefore to receive 
machines, processes, and tools; (2) with special use, purpose, or 
object-treated title containing the name of the use, purpose, or 
object : (3) with "type" title, usually a name or a name with a qualify- 
ing adjective; (4) with a title of a part or subcombmation, also a 
name . 

Example: In Class 90, Gear-Cutting, Milling and Planing, are to be found sub- 
classes entitled ''Gear-cutting," certain machines being peculiar to that use; also 
other subclasses with the general functional title "Planing." subordinate to which 
are the special use subclass "Planing. Soft metal." and the type subclass "Planers" 
divided into two coordinate subclasses, "Reciprocating bed" and "Reciprocating 
cutter," and several subordinate "part" subclasses, including "Tool-feeds" and 
"Tool-heads." The adjective form of the title "Planers, Reciprocating bed," indi- 
cates a type subclass. If the title had been Planers, Reciprocating beds, the indica- 
tion would be that the subclass was a part subclass to receive planer beds only. In 
the class referred to for illustration, "Tool-feeds" and "Tool-heads" indicate sub- 
classes for parts and not for^ types of planers having tool feeds. 

(12) In arranging the divisions of a class, such arrangement should 
be sought as will minimize the need of cross-references. Search for 
any particular matter can not always be limited to one group without 
such extensive cross-referencing as would in some cases defeat the 
purpose of classification. Forming the subdivisions of a class accord- 
ing to the total similarities of the inventions, rather than according 
to some selected more or less important characteristic, and arranging 
them in the correct order of superiority and inferiority, with care to 
maintain throughout the schedule the relative positional values of 
the several selected bases of division, will ordinarily in a closely 
bonded class limit the search for any single invention to the subclass 



36 CLASSIFICATION OF PATENTS. 

particularly suited to receive it and some subclasses preceding that 
one, excluding from the necessity of search the subclasses succeeding. 

Example: In Class 80, Metal-Rolling, it would not be expected to find any tube- 
rolling mill lower in the schedule than the tube-rolling subclasses, but a tube-mill 
might be found higher up in "Heating and rolling," "Drawing and rolling," etc. 
No concave and roll combination should be found succeeding the subclass of 
"Concave and roll," but it may be found under subclasses above, such as "Tubes, 
Screw-threads," etc. No rolls should be found lower than the subclass of "Rolls," 
but they may be found in many subclasses above. 

DEFINITION . 

(13) Having some knowledge of the nature of the materials about 
to be classified, a tentative definition of a class to be formed may 
be framed, which may be either written down or merely carried in 
mind, to serve as a tentative guide. This tentative definition must 
be considered as subject to change to any extent by the fuller 
knowledge obtained by careful consideration of the material. After 
a full knowledge of the materials to be classified has been acquired, 
it will be necessary to frame a careful definition of the class, and 
also of each subclass whose title does not unequivocally indicate 
what is contained in it. 

(14) A definition of any class should state the ^ Equalities and 
circumstances possessed by all the objects that are intended to be 
included in the class and not possessed completely by any other 
objects." A proper definition should not ordinarily contain the 
name of the thing defined. ^'Definitions in a circle" are, of course, 
worthless. A definition should be exactly equivalent to the species 
defined and should not be expressed in obscure or ambiguous 
language, but should employ terms already defined or perfectly 
understood. It should not be in negative form where it can be 
affirmative. If the class of objects has a peculiar property, the 
naming of that may serve as a definition. If no peculiar property 
can be detected, the definition should name more than one quality 
or property. Several different classes may have one or more prop- 
erties alike, but as the number is increased the likelihood of there 
being others having the same properties is decreased. The briefest 
possible statement of such properties or qualities as are possessed 
by aU the objects of a class and not completely possessed by any other 
objects, which will suffice to distinguish the class from other classes 
and determine its position in the general classification, will be most 
satisfactory. To define any species, the genus having been defined, 
the genus should be named and the difference added. Of course, 
no generic definition should contain any limitation not characteristic 
of every species of the defined genus. In seeking qualities by which 
to describe a geims or species, no accident should be selected. 

Example: Suppose there be marked out and defined as a genus all means whereby 
one form of energy is transformed into another form of energy and no more, and the 



CLASSIFICATION OF PATENTS. 37 

genus be named energy-transformers. We may then name, as species, energy-trans- 
formers that are motors and energy-transformers that are not motors. Motors may be 
defined by merely naming the genus energy-transformers, and stating the difference, 
to wit, continuously transforming energy into cyclical mechanical motion. Then the 
definition will be: Energy-transformers that are adapted to continuously transform 
energy into cyclical mechanical motion. The non-motor division will retain the 
genus definition. 

It would not be illiuninating for a searcher having little familiarity with the textile 
arts to look under the title "'Carding' ' and find that carding is defined as a means for 
carding fiber. 

Even though the first steam-engine invented had been used to run a gristmill, the 
accident of its use as a part of a gristmill would hardly warrant the definition of a 
steam-engine as a means to grind corn. Nor would a hammer be properly defined as 
an instrument to drive nails or to crack nuts or to forge horseshoes, even though a 
patent should not mention any use other than one of these and should lay heavy 
emphasis on the special value of the hammer as a nut cracker, nail driver, etc. 

(15) In those cases where the title is so obvious that definition is 
superfluous, explanatory notes may be substituted and will usually 
be found helpful. 

CROSS-REFERENCES AND SEARCH-NOTES. 

(16) Inasmuch as nearly every patent discloses unclaimed matter 
that is classifiable separately from the claimed matter, it is clearly 
impossible to cross-reference every disclosure of ever}^ means in every 
patent. Many things must be taken as conventional, obvious, or 
well known, and the good judgment of the classifier is bound to be 
exercised in cross-referencing matter disclosed but not claimed to be 
the invention of the patentee. 

(17) A mere part or element should rarely be cross-referenced 
from an element class to a superior combination class. An element 
forming part of a combination in a superior class should, if claimed, 
be cross-referenced to the element class and also if not claimed if it 
seems to be not merely a conventional form, and patents having 
claims for more than one differently classifiable invention should 
always be cross-referenced unless such an arrangement of subclasses 
with search-notes is -substituted as will guide the searcher to all 
places where the material may be found. Claimed matter additional 
to that which controls the classification, if belonging in the same class, 
should be cross-referenced into a succeeding subclass. Cross-refer- 
ences of unclaimed disclosure may be in either direction. 

(18) To supplement or take the place of cross-referencing, more or 
less elaborate search-notes are needed, giving directions and sugges- 
tions for further search, setting out the relationship between classes 
and subclasses, and drawing distinctions by example. Search- 
notes should indicate other classes or subclasses in which the subject- 
matter of the group to which the search-notes are appended is likely 
to form a part of a more intensive combination, also analogous mat^ 



38 CLASSIFICATION OF PATENTS. 

ter that might serve as a reference for a broad claim. They need not, 
in general, indicate where parts or elements of the subject-matter 
which are common also to other classes can be found, because the 
index of classes contains the necessary information. For example, it 
is not necessary in every machine-class to indicate by search-notes 
where machine-elements and static parts may be found, nor in a class 
of wooden boxes to point out where the nails, screws, hinges, or 
locks that may form a part of the box are classified. 

DIAGNOSIS TO DETERMINE CLASSIFICATION. 

(19) Inasmuch as nearly every patent contains disclosure that is 
claimed and also disclosure that is not claimed, it has been deemed 
advisable to establish the general rule that where the claimed and 
imclaimed disclosures are classified in different classes or subclasses 
the invention both disclosed and claimed shall determine the placing 
of a patent (or a pending application) rather than any selected in- 
vention that may be disclosed but not claimed. "Not claimed" covers 
means that may form an element only of a claim as well as means not 
referred to in any claim. (See exceptions in Rules 21 to 22 inclusive.) 

Example : A patent discloses and claims a dash-pot but illustrates it in such relation 
to a metal-planing machine as to utilize it for checking the movement of the bed at 
one end of its path, or in connection with an electric generator to aid in effecting the 
brush adjustment; the patent should be classified in the subclass of Dash-pots. If 
the classifier finds the disclosed organization of dash-pot and planer or dash-pot and 
generator more than a conventional illustration of an obvious use, he should note a 
cross-reference to Planers or Electricity, Generation. A patent discloses an internal- 
combustion engine associated with a specific form of carbureter; the claims relate 
to the engine parts only; the class of Internal-Combustion Engines should receive 
the patent, and a cross-reference should be placed in Carbureters. A patent discloses 
and specifically claims the combination of a rail-joint comprising abutting rails, fish- 
plates, and specific bolts; the patent goes to an appropriate class of rail-joints, and 
if the bolt is more than a mere obvious conventional bolt, a cross-reference should be 
noted for the appropriate subclass of Bolts. 

(20) The totality of the claimed invention should be selected when 
possible to determine the appropriate class in which to place a patent. 
The entire expression of the invention will usually be set forth in the 
most relatively intensive claim. ^ But mere difference in the scope 
of claims should not make a difference in classification. 

1 All terms have a meaning in extension and in intension. The meaning of a term in extension consists 
of the objects to which the term may be applied; its meaning in intension consists of the qualities neces- 
saril ,' possessed by objects tearing that name. The term "motors" in extension means all motors- 
electric, gas, water, spring, weight, etc. "Motors" in intension means instruments to convert some f jnn 
or mani:estation of energy into periodical or cyclical motionof a body. As the intension increases the exten- 
sion decreases, and vice versa. There must be more motors than there are electric motors, and electric 
motors have more quali.ications than are common to all motors. Comparison of arts and instruments with 
respect to their extension and intension for classification purposes should be made between comparable 
qu ilities. A claim for a steam-engine may be very specific whi'.e a claim for a reaper may be very broad; 
liere there is no comparable relationship, and the terms intensive and extensive do not have the relative 
sigiii icauce most useful in classification. But when a patent or application contains claims for mechani ^m 
pecLiliir to electric motors and other claims for mechanism common to electric motors and other kinds of 
motors, t".;e claims for the electric motor would control the classification. 



CLASSIFICATION OF PATENTS. 39 

(21) Where a patent discloses but does not claim a combination 
of proper scope to be classified in a combination subclass and claims 
merely a detail classified in a subclass lower in the schedule, both in 
the same class, if the subclasses are so related that the combination 
always involves the detail so that a search for the detail must neces- 
sarily be made in the combination subclass, the patent may be placed 
in the combination subclass. This avoids the need of a cross refer- 
ence into the combination subclass, and a lack of a copy in the detail 
subclass is immaterial, as it is seen in the completion of the search 
through the combination subclass. (See Rule 19.) 

Example: A patent for a saw-making machine discloses dressing, jointing, and 
gaging mechanisms; it claims dressing and jointing only. There is a subclass for 
dressing, jointing, and gaging, and a su'Dclass for dressing and jointing. In this case 
the patent may } e placed in the first-mentioned sif class, as that must te searched 
always when the second-mentioned one is searched, cross referencing in this situation 
being of little value. 

(22) Where a subclass with a generic title has indented thereunder 
a species type-subclass bearing the title of the generic subclass 
ciualified by a difference, any patent which claims an invention fall- 
ing within the genus subclass and discloses the qualification of the 
species type-subclass should be classified in the latter whether or not 
the entire disclosure is claimed. (See Rule 19.) 

Example: 

Class 29. — ^Metal Working. 
Machine chucks and tool sockets — 
Cam closing — 

126. Scroll— 

127. Bevel pinion or ring. 

If a patent claimed only the scroll of a scroll-chuck, lut disclosed it in connection 
with a bevel pinion and ring, it should be classified in su'j class 127, Bevel pinion and 
ring, and not in subclass 126, Scroll, although if there were no disclosure of the bevel 
pinion and ring it would go in subclass 126. Any search for scrolls must b e prosecuted 
through all subclasses that include "Scroll" in the title. 

(23) Where, as in the case of patents that show and claim a combi- 
nation that as matter of common knowledge is not new except in one 
of its elements, to classify a patent strictly in accordance with rule 
would result in placing the patent where it would serve no useful pur- 
pose as a reference and having to cross-reference it to a class where 
it would serve a useful purpose, it is best to classify the patent in 
the class to which the element would take it. (See Rule 19.) 

Example: A patent claiming a wheeled vehicle, broadly, in com' ination with an 
internal-combustion engine comprising a cylinder, a crank-case, a piston and suitably- 
connected crank, a valve opening into the crank-case, and a valve in the piston open- 
ing into the cylinder, may '» e advantageously classified as an internal-combustion 
eigine notwithstanding the alleged invention is for a motor vehicle. 

(24) In order to meet the situation respecting the classification 
o' those patents that indiscriminately claim an article of manufacture 



40 CLASSIFICATION OF PATENTS. 

defined only by the material of which it is made and those patents 
that claim those materials, leaving to the specification information 
regarding the designed uses, patents for articles defined only by their 
ingredients specifically set forth ma}^ be placed in the composition 
of matter or material class. (See Rule 19.) 

Example: A patent having a claim for a cutter made of an alloy of iron, tungsten, 
and manganese would be classified with Alloys; a patent claiming a box made of 
paper composed of two layers united by a solution of asphaltum should go to the class 
of Laminated Fabric and Analogous Manufactures, rather than to paper boxes; and 
a patent for a house having its exterior coated with equal quantities by volume of 
carbonate of lead and oxid of barium suspended in a vehicle of linseed-oil would be 
classified as a paint rather th.an as a house. 

(25) An alleged process of utilizing a specifically-defined compo- 
sition or material which consists in merely applying it to the use it 
was designed for may be classified as a composition or material 
rather than as a process. (See Rule 19.) 

Example: A process of painting the bottom of a marine vessel which consists in 
applying thereto a composition consisting of sulphate of copper, powdered metallic 
zinc, chlorid of antimony, and hyposulphite of soda, in a. vehicle of linseed oil, 
would be more usefully classified as an antifouling paint than as a coating process, as 
the invention would hardly be distinguishable from a paint claimed as such and 
described for use on submarine surfaces. 

(26) An alleged process consisting merely in the use of a particu- 
larly-defined machine or similar instrument operating according to 
its law of action will ordinarily be classified in the class or subclass 
where the machine belongs. But if in addition to defining the opera- 
tion of a particular machine the claim also specifies acts not per- 
formed by the machine, the classification should be in the class or 
subclass in which the process belongs. (See Rule 19.) 

Example : Thus a claim for a method of rolling an iron plate which consists in pass- 
ing an iron blank between a pair of rolls arranged horizontally in juxtaposition one 
above the other and geared together so as to rotate in opposite directions, and causing 
an idle roll supported in bearings on the roll-housings to bear against the central 
portion of the surface of one of the first pair of rolls on the upper side thereof, should 
be classified as a rolling-mill, while if to that claim were added the steps of doubling 
the sheet after one passage between the rolls, again passing between the rolls, again 
doubling, and then passing the now four-ply pack between the rolls side wise or turned 
90 degrees to the direction in which it had previously been fed, the classification 
should be with processes of sheet-metal manufacture. 

(27) In the absence of settled rules defining permissible joinder of 
inventions, there may be in one patent claims for one or more or all 
of the classes of invention named in the statute, to wit, machine, art, 
manufacture, and composition of matter. There may also be claims 
to several more or less related inventions in the same statutory class 
of invention but each belonging to a different industrial art. (1) 
Where different main classes are involved, the patent will bo classi- 
fied by the most intensive invention, without regard to the statutory 



CHASSIFICATION OF PATENTS. 41 

class to which it belongs. (2) Where different subclasses of the same 
class are involved, the patent will be classified in that one of the sev- 
eral subclasses defined to receive the several inventions which stands 
highest in the schedule of subclasses. 

(28) Where a patent contains claims for all or a plurality less than 
all of the statutory classes, the general rule of preference or superi- 
ority of the several classes or subclasses is that represented by the 
following order, to wit: (1) Machine (or other operative instrument); 
(2) Art; (3) Manufacture; (4) Composition of matter. This order 
is, in a general way, the order 'of intensiveness of the several kinds of 
invention. (See Rules 29-35.) 

Example: An automatic screw-machine, peculiarly adapted to carry out a process 
of making a novel form of machine-screw out of a new iron alloy, and having a claim 
to the machine, to the process, to the screw, and to the alloy, would be assigned to 
Metal- Working, Combined machines, and, if all claims were allowed, cross-referenced 
to Bolt and rivet-making processes, to Bolts, and to Alloys. If the claim to any one 
or two of the subjects were eliminated, the order of preference or superiority and the 
order of cross-referencing would remain the same. 

(29) Patents containing a plurality of claims for several different 
statutory kinds of invention that are classifiable in different main 
classes, and wherein the rule of relative intensiveness varies from the 
order Machine, Art, Manufacture, and Composition of matter, may 
be diagnosed and classified as directed in the following paragraphs 
(30 to 35). 

(30) Where a patent contains claims for a process and for an appa- 
ratus susceptible of use as an instrument in carrying out the process, 
but not peculiar to that use, or for an apparatus adapted to carry out 
but one step or only a part of the process, the process claim, boiag in 
this instance the more intensive, would control the classification. 
(See rule 28.) 

Example : In a patent containing a claim for a process of roasting ore and then col- 
lecting the fumes, and another claim for a roasting furnace that is a mere material-heat- 
ing furnace, the process claim would control; whereas, if one claim were for a method 
of roasting ores consisting of stirring the ore, applying heat to the same, and collecting 
the solids from the fumes, and the other claim were for a heating furnace having a 
stirrer and a fume arrester, the apparatus claim would control. And if a patent con- 
tained claims for a process of roasting ores, and other claims for a furnace susceptible 
of use in carrying out the process but equally useful in annealing glass or steel articles, 
the process claim would control. 

(31) Where a patent claims a specified article of manufacture or 
other product, and also an instrument for making a part only of that 
specified article or other product, the product claim, being mors 
intensive, should control the classification; so also in case of a claim 
for a product and a claim for an instrument performing any minor 
act with respect thereto. (See Rule 28.) 



42 CLASSIFICATION OF PATENTS. 

Example: Where a patent claims a particular construction of a riveted joint, and 
also a tool for calking the rivet, and where a patent claims a particular construction of 
shoe, and also a buttonhook for buttoning said shoe, the article and not the tool claims 
control. 

(32) Where a patent contains claims to a process and a product, 
the process claims govern the classification in those cas^s where search 
among machines for making the product would have to be made, and 
such processes would be classifiable on the basis of the mode of opera- 
tion, usually in the same class with machines for practicing such 
processes. (See Rule 28.) 

Example: A patent having a claim for a process of making bifocal lenses, consisting 
in grinding the surface of one piece of glass to form a convex lens, heating another piece 
of glass until it is plastic, then forcing the ground surface of the first-named piece into 
the body of the latter and gradually cooling the lens-blank thus formed ; and also a 
claim for a bifocal lens composed of two pieces of glass weld-united, would be classi- 
fied in Glass-manufacture and cross-referenced into lenses. Or a patent having a claim 
to a process of making a metal plate with elongated perforations, consisting in forming 
round perforations in the plate and subsequently rolling the plate, thereby thinning 
and elongating the plate and elongating the openings, and also a claim to a metallic 
plate having relatively long and narrow perforations, would be classified on the basis 
of the process claim. 

(33) Where a patent claims both process and product, and the 
aUeged process is disclosed in the product, so that search would have 
to be made in the appropriate class of products, the product will be 
adopted as the basis of classification, and classification will be in 
the appropriate product class. (See Rule 28.) 

Example : A claim for a process of making a pencil consisting in assembling a core 
of graphite with a sheathing of wood, and attaching a cap of rubber-composition to 
one end, would be classified as a pencil rather than as a process, because conception 
of the article is inseparable from- the process and search must be made in the article 
class. 

(34) Where a patent claims a process of making a composition of 
matter, and also the composition of matter, the claims will be classi- 
fied in general in accordance with the classification of the composi- 
tion of matter in all cases where the process is peculiarly adapted to 
produce the composition, as by setting forth the introduction or 
assemblage of particular ingredients, since those processes that in- 
clude the selection of particular ingredients necessitate search among 
compositions having such ingredients. (See Rule 28.) 

Example: A patent having a claim for a composition consisting of a mixture of 
caoutchouc and casein, and a claim for the process of preparing a rubberlike sub- 
stance which consists in adding undissolved raw caoutchouc to casein and thoroughly 
mixing and kneading the mass, would be classified according to the composition, 

(35) Where a patent claims a product such as a specific article 
of manufacture, or a specific composition of matter, and also claims 
a process of general application for making one of the parts of the 
article or one of the ingredients of the composition, the product claim 
should control the classification. (See Rule 28.) 



CLASSIFICATION OF PATENTS. 43 

Example : If a patent claimed a woven textile fabric having the yarns interlslced 
in a defined relation, and a process of spinning a yarn utilized in the fabric; or if a 
patent claimed a varnish composed of shellac, dissolved in wood alcohol, and a pig- 
ment, and also contained a claim for distilling wood to obtain the alcohol, the product 
claim would control the classification in each instance, and the process would be 
cross-referenced . 

(D) PROCEDURE IN RECLASSIFYING WITHIN EXAMINING 

DIVISIONS. 

(1) Do PxOt start to make a new class or revise an old one with pre- 
conceived fixed notions respecting its scope and the particular sub- 
divisions required. Wait until all patents pertinent to the subject 
have been seen and adequate knowledge of them acquired. In other 
words, make no a priori classification but discover and assemble all 
the facts and from them make your inductions. Then the common 
characteristics of the subject-matter of the class may be intelligently 
defined, the limitations of the class marked out, and its relation to 
other classes set forth. Bear in mind that the Patent Office classi- 
fication deals with the subject-matter of the useful arts rather than 
merely with existing classes, and that it is not therefore essential to 
retain classes that are found to be composed of unrelated or too 
distantly related units. 

Assuming that the work of reclassification is undertaken by exam- 
iners who are already experienced in the subject-matter to be classi- 
fied, procedure as follows is recommended: 

(2) Utilizing your previously acquired knowledge of the patents in 
the class you are about to revise, subdivide the existing subclasses 
into bundles, so as to assemble in each bundle those patents deemed 
to have the closest resemblance to each other. For the purpose of 
this assemblage, consider each patent as an entirety and not with 
reference to various more or less important parts of that entirety. 

Example : An apparatus comprising in alleged combination a means for decanting 
water, a means for electrolytically depositing impiuities, and a means for filtering the 
water, should not be classified either as a decanter, an electrolytic apparatus, or a 
filter, but should be classified as a combination apparatus (taking it to the general art 
of hquid purification). So also the combination of a rotary printing-press with a 
folding mechanism, and a wrapping mechanism, should not be classified merely as a 
rotary printing-press, a folding machine, or a wrapping machine, but should be 
classified as a combination of the several mechanisms as an entirety whose functions 
carried out in proper order produce a printed and wrapped newspaper. 

(3) Write an approximate or tentative definition of the matter 
thus assembled in each bundle and attach it to its appropriate bundle. 

(4) Where it appears that the subject matter of any bundle formed 
from the patents of any subclass is analogous to matter in other sub- 
classes of the same class or in other classes, a note should be added 
to that eft'ect so that this matter may be given special consideration. 



44 CLASSIFICATION OF PATENTS. 

(5) When the same examiner or different examiners are working 
on different subclasses containing analogous matter, parallel lines of 
subdivision should be followed wherever possible, in order to effect 
an arrangement that will facilitate comparisons. 

(6) When subdividing a group of more or less complex organized 
structures or mechanisms, note should be taken of subcombinations 
that form or it is thought should form the basis of other subclasses, 
either in the same or different classes, into which those details may be 
collected, either classified therein originally or by cross-reference. 

Example: Assuming that the combination of press, folder, and wrapping mecha- 
nism, referred to in a preceding paragraph is to be classified in a class of Printing, on 
the entirety as a combination having the function of printing, plus other functions, 
and that folding and also wrapping are separately classified, then the particular type 
of press should be selected to be cross-referenced into a press-type subclass of the class 
of Printing, such as "Presses, rotary," while the folding mechanism and the wrapping 
mechanism would be noted for cross-reference to other appropriate classes. Also, 
any part of the printing press, such as the inking mechanism, specifically described, 
should be noted for cross-reference into a subclass of Printing designed to receive the 
inking mechanism as a part of the printing press. 

(7) After a knowledge of the material of tne class has be3n obtained 
by estimating the resemblances between the individual patents that 
have been assembled in the several groups, comparison of these groups, 
represented by the bundles of photolithographs, by the aid of the 
approximate definitions and notes attached can be made. It can 
then be decided whether all of these groups are to be retained in the 
proposed class, and the retained groups can be organized into a class 
with the subclasses arranged so as to bring those subclasses having 
the strongest resemblances in closest relation, and in such order as to 
comply with the conventions adopted in the official classification. 
It will probably be necessary to have one subclass or group as broad 
as the definition of the class, to take unclassifiable matter and to 
provide for possible future inventions. 

(8) Up to this point, more or less cursory attention may be given 
individual patents ; but when an arrangement of subclasses shall have 
been tentatively adopted it will be necessary to consider each patent 
carefuUy to ascertain whether it is properly placed. 

(9) Patents that, considered as an entirety, cover means not 
peculiar to the class or subject-matter being revised, should, in general, 
when assembled in groups as indicated, have a note attached indi- 
cating not only want of limitation to the subject-matter of the class 
but also a more appropriate class to receive them if such there be. 
Although a very large proportion of patents. can be accurately classi- 
fied as indicated by their titles and stated uses, the mere fact that in a 
patent found in a class the invention is called in the specification or 
claims by a name peculiar to the class is not of itself a reason for con- 



CLASSIFICATION OF PATENTS. 45 

sidering it peculiar to the class. A gas and liquid contact apparatus 
may be called a heater, a cooler, a gas-washer, a water-carbonator, a 
condenser, a disinfecter, an air-moistener, and so on, depending upon 
accident of use. If there are not elements in some claim to confine 
the means described distinctively to what it is called, or if there are 
no functions necessarily implied in the means claimed peculiar to the 
named use, the patent should not be kept in the class unless there is 
no other class in the office that can receive it. 

Example: Where the matter claimed is a metal beam of peculiar cross-section, it 
should ] e classified with other metal beams, as in Class 189, Metallic Building Struc- 
tures, even if it is named in the application as a beam of particular use, as a railroad- 
tie, car-sill, bridge-tie, etc. Should a mere dash-pot he found classified in Class 171. 
Electricity, Generation, a note should be attached indicating that it belongs in the 
appropriate element class. 

(10) In giving this final careful attention to the patents, each 
should also be scanned to see whether it contains matter that should 
be cross-referenced. A few lines obscurely located in a specification 
may contain a disclosure of a most valuable invention. No class 
can be deemed complete until the disclosures appropriate to it found 
as parts of more complex inventions in other classes, or disclosures 
of analogous matter in other classes, are either cross-referenced into 
it or cross search-notes made. 

(11) To indicate cross-references, from one subclass to another 
within the class or from one class under consideration into another 
class, attach a small slip of paper to the patent and mark on the slip 
the subclass number in which the cross-reference shall be mounted. 
If the matter to be cross-referenced relates only to a portion of a 
voluminous patent, the portion of the specification and drawing to 
be cross-referenced should be indicated. If the cross-reference falls 
outside the class, the^ class number should be noted in addition to 
the subclass number. 

(12) Should it be found that the handling of copies in making 
examinations detaches the cross-reference slips, it may be advisable 
to mark lightly but Ipgibly in pencil on the lower right-hand corner 
of the examiner's photolithograph the number of the subclass or 
subclasses into w^hich it is to be cross-referenced, or the number of 
the class and subclass in case it is to be cross-referenced to another 
class. 

(13) Whether cross-reference notations are written on a separate 
slip or on the photolithograph, the number of the class and subclass 
into which a patent is to be cross-referenced should always be pre- 
ceded by X (thus X 101-23) in order to distinguish the original 
classification notation from the cross-reference notation and enable 
sorting and indexing to be done without confusion. 



46 CLASSIFICATION OF PATENTS. 

(14) To indicate cross-references from other classes into the one 
being reclassified, set down the number of the patent in a notebook, 
placing after the number (1) the class and subclass in which it is 
classified; and (2) the number of the class and subclass in which it 
is to be cross-referenced. 

(15) Should new subclasses be formed or transfers of patents be 
determined on, and lists of the patents, instead of copies thereof, 
be furnished clerks for the purpose of making such subclasses and 
transfers and correcting the official indexes and other records, each 
patent should be listed by number in column to the left of a sheet of 
paper or notebook, and opposite each patent number on the same 
sheet should be written (1) the number of the class and subclass in 
which it is officially classified; (2) the number of the class and sub- 
class to which it is intended to transfer it; and (3) the numbers of 
the classes and subclasses, preceded by X, into which it is intended 
to cross-reference it. 

Note: Even though examiners engaged in reclassifying are confident of their a^:ility 
to classify and arrange on better principles than those that have been applied thus 
far in the classification, they ought, nevertheless, to follow those principles under 
which one-half of the patents have been classified. Until the Commissioner of Pat- 
ents orders examiners to classify on other principles, it is expected they will follow 
those now established. 

o 



I 



